Switched AppBus for ResultHandler, Controller for Helper. Added the basics for LifecycleControllers and implemented it for BriarActivity and NavDrawerActivity

Forum Sharing Client UI

This changes `ShareForumActivity` to use two fragments to facilitate
forum sharing with the new Forum Sharing Client backend.

The `ContactSelectorFragment` allows the user to select a
number of contacts. If there is an ongoing sharing session or the forum
is already shared with the contact, it is disabled in the list. If there
is at least one contact selected, a button appears in the toolbar that
brings the user to the `ShareForumMessageFragment` where the user can
write an optional message to be send along with the invitation.

After sending an invitation, the user is brought back to the forum that
she shared and there is a snackbar showing up briefly to indicate the
successful invitation.

The invitation is shown along with the message within the private
conversation of each contact. The person who shares the forum also sees
the invitation and the message as outgoing messages that also display
the current status of the messages.

A notification is shown like for other private messages as well.

Please note that this commit does not include a way for users to respond
to invitations. This is in MR !172. Both MRs are based on the new backend in !170.

![device-2016-05-03-182928](/uploads/48499ca4c149a8e7f13f8b28a24537ad/device-2016-05-03-182928.png)
![device-2016-05-03-182855](/uploads/5f49c43bf8f39780862247848a5b9c27/device-2016-05-03-182855.png)

See merge request !171

Modernize AvailableForumsActivity

Turn list of available forums into a `BriarRecyclerView` with XML layout.
Allow to respond to forum invitations from the list of available forums.
The user can either accept or decline an invitation.

![device-2016-05-03-141150](/uploads/0998877d47fb7a3eafe3a90f917d8716/device-2016-05-03-141150.png)

See merge request !172

This changes `ShareForumActivity` to use two fragments to facilitate
forum sharing with the new Forum Sharing Client backend.

The `ContactSelectorFragment` allows the user to select a
number of contacts. If there is an ongoing sharing session or the forum
is already shared with the contact, it is disabled in the list. If there
is at least one contact selected, a button appears in the toolbar that
brings the user to the `ShareForumMessageFragment` where the user can
write an optional message to be send along with the invitation.

After sending an invitation, the user is brought back to the forum that
she shared and there is a snackbar showing up briefly to indicate the
successful invitation.

The invitation is shown along with the message within the private
conversation of each contact. The person who shares the forum also sees
the invitation and the message as outgoing messages that also display
the current status of the messages.

A notification is shown like for other private messages as well.

Please note that this commit does not include a way for users to respond
to invitations.

Turn list of available forums into a BriarRecyclerView with XML layout.
Allow to respond to forum invitations from the list of available forums.
The user can either accept or decline an invitation.

Prevent old forum sharing messages from causing spurious exceptions.

New List of Forums

The adapter of the `ForumListFragment` has been changed into a
`BriarRecyclerView` and all its code has been adapted and simplified
accordingly.

All UI of the forum list is now defined in XML layouts. This enabled me to move the snackbar into onCreate().

Before:

![device-2016-05-03-165331](/uploads/961cc2c043464f446584de4ae0ad527b/device-2016-05-03-165331.png)

After:

![device-2016-05-03-165117](/uploads/e22ede3e9a3330762b3ae84f86ca6ec5/device-2016-05-03-165117.png)


See merge request !175

Try harder to connect to contacts

* When an outgoing connection is lost, try to reconnect to the contact straight away
* Use periodic polling for Tor, regardless of whether our hidden service descriptor has been published
* Reduce polling intervals for all plugins (this can be reverted if we solve the connectivity issues)

Closes #262, #314. Hopefully helps with #361.

See merge request !177

Forum Sharing Integration Tests

This adds integration tests for these cases:
* normal invitation session where invitee accepts
* normal invitation session where invitee declines
* session where invitee leaves again after she joined
* session where sharer leaves after invitee has joined
* session where sharer leaves before invitee can respond
* sharer reuses the session ID of the previous session
* after accepting the invitation, the invitee invites the sharer to the same forum
* after session contacts delete each other and session states get cleaned up

Closes #339

See merge request !173

Forum Sharing Client Backend

This MR replaces the old `ForumSharingManagerImpl` with a new one
which is based on state machines and the `ProtocolEngine`.

There is a `SharerEngine` and a `InviteeEngine` that take care of state
transitions, messages, events and trigger actions to be carried out by
the `ForumSharingManagerImpl`. This is all very similar to the
Introduction Client.

The general sharing paradigm has been changed from sharing as a state to
sharing as an action. Now the UI can allow users to invite contacts to
forums. The contacts can accept or decline the invitation. Also, the
Forum Sharing Manager is notified when users leave a forum.

Please note that you will need the UI to actually test this. It is coming up soon in another MR.

Closes #322

See merge request !170

Store a fixed number of recent IP addresses, padded with fakes

Closes #302

See merge request !159

Includes parallel improvements to Bluetooth key exchange UI.

Use control port to create and set up Tor hidden service

Closes #149

See merge request !160

Remember the selected fragment from the NavDrawer

and stay in it when configuration changes

Closes #370

See merge request !176

Do not allow session ID reuse and clean up sessions for introducee

It was possible that a malicious introducer sends new request with the
same session ID that was used previously and thus causing introducees to
have multiple states for the same session ID.
This commits prevents that from happening and adds an integration test
for that scenario.

Also if an introducee removes an introducer, all past session states
will be deleted from the database. For this, a test was added as well.

Closes #371
Closes #372

See merge request !179

It was possible that a malicious introducer sends new request with the
same session ID that was used previously and thus causing introducees to
have multiple states for the same session ID.
This commits prevents that from happening and adds an integration test
for that scenario.

Also if an introducee removes an introducer, all past session states
will be deleted from the database. For this, a test was added as well.

Closes #371
Closes #372

The adapter of the `ForumListFragment` has been changed into a
`BriarRecyclerView` and all its code has been adapted and simplified
accordingly.

All UI of the forum list is now defined in XML layouts.

This adds integration tests for these cases:
* normal invitation session where invitee accepts
* normal invitation session where invitee declines
* session where invitee leaves again after she joined
* session where sharer leaves after invitee has joined
* session where sharer leaves before invitee can respond
* sharer reuses the session ID of the previous session
* after accepting the invitation, the invitee invites the sharer to the same forum
* after session contacts delete each other and session states get cleaned up

Closes #339

This commit replaces the old ForumSharingManagerImpl with a new one
which is based on state machines and the ProtocolEngine.

There is a SharerEngine and a InviteeEngine that take care of state
transitions, messages, events and trigger actions to be carried out by
the ForumSharingManagerImpl. This is all very similar to the
Introduction Client.

The general sharing paradigm has been changed from sharing as a state to
sharing as an action. Now the UI can allow users to invite contacts to
forums. The contacts can accept or decline the invitiation. Also, the
Forum Sharing Manger is notified when users leave a forum.

Closes #322