Use namespaced strings for client IDs

Closes #557

See merge request !393

Mark private messages read properly

Depends on !386.

This branch uses the same approach as forums to mark messages read, i.e. each message is marked read when it becomes visible, rather than marking all messages read in a batch when the activity finishes. This fixes two problems: messages not being marked read when isFinishing() is false, for example when leaving the activity via the home button, and a race condition between updating and loading the group count when leaving the activity, resulting in a stale unread message count in the contact list.

Closes #196.

See merge request !388

Broadcast GroupMessageAddedEvent for the UI to update when received

Closes #733

See merge request !390

Create GroupDissolvedEvent and react to it

This MR also makes the private group list react to incoming group invitations (once they are implemented).

![device-2016-11-07-155240](/uploads/84ed51cf72bf2c7c597a0fd68b5d868c/device-2016-11-07-155240.png)
![device-2016-11-07-155302](/uploads/446c98d70d674d0bcd79bfb7682dfed5/device-2016-11-07-155302.png)

Closes #736, #737

See merge request !392

Also react to incoming group invitations

Show Notifications for Group Messages

Closes #734

See merge request !391

Return to group after not inviting new members

This MR also closes the keyboard when returning from the message fragment.

Closes #735

See merge request !389

Fixed asynchronous Activity leaks in Fragments

If a Fragment has been detached its `getActivity()` method will return null, providing numerous crash possibilities within the app.

My approach to fixing this is to make Fragments use their own `runOnUiThreadUnlessDestroyed` method, which also checks if the Fragment has been detached before running the Runnable

Closes #714

See merge request !387

Also close keyboard when returning from message fragment

Use contact ID rather than messaging group ID to identify conversation

We originally used the private messaging group ID to identify the private conversation, but now that the conversation includes messages from multiple clients it's more appropriate to use the contact ID.

This refactoring isn't urgent - I've had the branch lying around for a while, but I'm putting it up for review because #734 will touch some of the same code.

See merge request !386

Allow messages to be deleted in delivery hook

Closes #643

See merge request !385

Add unit tests for KeyManagerImpl

This also creates a `TransportKeyManager` interface and a factory for that to be able to test things separately.

Closes #205

See merge request !380

interface and a factory for that.

Let only the creator invite new members to private groups

A little bug I noticed when reviewing the implementation of the invitation protocol.

See merge request !383

Remove new member announcement and add signature to join message



See merge request !384

Replace transaction.setComplete() by database.commitTransaction()

Closes #674

See merge request !374

Improve QR code workflow slightly

* Improve wording so contacts know they need meet up to scan
  and scan each other's codes
* Use consistent progress bar styles

Closes #348

See merge request !381

* Improve wording so contacts know they need meet up to scan
  and scan each other's codes
* Use consistent progress bar styles

Add Unit Tests for ClientHelper

Closes #724

See merge request !379

Don't throw IllegalStateException if BDF input is incomplete

Closes #731

See merge request !378

Limit the depth of nested BDF structures

Closes #518

See merge request !375