Remove MAX_GROUP_DESCRIPTOR_LENGTH

Closes #441

See merge request !224

Closes #441

Forum improvements

Forum Activity improvements:

* Orientation changes now restore the activity properly, e.g. input text and state is retained
* Snack bar is now, when appropriate, clickable
* The bottom divider is no longer visible for the bottom entry
* Code refactoring for improved simplicity and less redundancy
* Timestamp check to ensure that new posts are not older than the latest post

Closes #426 
Closes #423 
Closes #424 

See merge request !218

Fixing fragment instance restore

Alas, it turns out that my neat way of integrating the Fragments into the dependency graph was not without problems. Me and @grote discovered that this presented us with a lot of problems on orientation changes as the Activity is re-created, and therefore parts of the dependency graph. The simplest solution was simply to abandon the idea, i.e. with this branch Fragments are no longer part of the dependency graph. 

See merge request !215

synched conversation and forum input

Closes #354

See merge request !219

Implement Blog Sharing Client

Closes #403

See merge request !220

Fix test broken by #78



See merge request !221

Blog Client with Factories and Validator

This implements a simple initial blog client that covers the basic blog actions, but no deletion/removal of blogs, yet.

Classes for Blogs and Blog Post Headers have been introduced along with the associated factories.

A `BlogPostValidator` has been added that validates incoming blog posts.

Closes #402
Closes #404

See merge request !212

New Trust Level Indicator Replaces The Stars

This implements a generic `TrustIndicatorView` with a `setTrustLevel()`
method which updates the drawable according to the `Author.State`.

It also removes unused files from the repo.

This is based on !212 and should only be merged after it.

Closes #78

See merge request !217

This implements a generic `TrustIndicatorView` with a `setTrustLevel()`
method which updates the drawable according to the `Author.State`.

Closes #78

This implements a simple initial blog client that covers the basic blog
actions, but no deletion/removal of blogs, yet.

Classes for Blogs and Blog Post Headers have been introduced along with
the associated factories.

A `BlogPostValidator` has been added that validates incoming blog posts.

Closes #402
Closes #404

fix persistance

Closes #433

See merge request !216

Add a UI for changing the password

Closes #390

See merge request !213

Fix NPE in ForumSharingStatusActivity by only accessing group in contact list

Only access group in contact list where it is guaranteed to exist.

Closes #430

See merge request !211

by checking if a group ID exists.

Closes #430

Client layer events for messaging

Adds and uses a new `PrivateMessageReceivedEvent` and eliminate the need for an event for adding local messages. Both done in separate commits.

This addresses part of #309

See merge request !208

Address Race-Condition in Forum Sharing

When Two Contacts Share Same Forum with each other at the same time a race condition causes them both to delete each other's invitation. This is solved by an Alice/Bob test as suggested in #388.

See merge request !205

Adds badges to the forum list that indicate unread posts

This MR adds  badges to the forum list that indicate unread posts. It does so by extending the compound view `TextAvatarView` and provides convenient setters that take care of the required UI changes. The new badge can also be used to indicate a problem with the forum.

![device-2016-06-02-134048](/uploads/133f365f5654be304f590a4f5b667d06/device-2016-06-02-134048.png)![device-2016-06-02-134453](/uploads/423a88f6306a558828181f0c539aa1cb/device-2016-06-02-134453.png)

I decided not to check if the forum is shared from someone or with someone and indicate a problem in this case, because this requires iterating two times over all contacts and their group metadata for each forum. If someone considers it important to check for this information, we can create a ticket for doing this within the forum and not in the forum list.

See merge request !207

Blog Fragment in Navigation Drawer with Tabs

This replaces the custom layouts in the navigation drawer with a
`NavigationView` and adds a menu entry for Blogs.

A Main Blogs fragment is added that holds a `TabLayout` and a
`ViewPager`. Five tabs are already added, but they just have a single
placeholder fragment that is to be replaced by the actual fragments.

Please note that the header in the navigation drawer is just provisional. I am sure @Megalox can design a better one.

![device-2016-06-02-191101](/uploads/ddffee792f67fad01158d7adc7ca904d/device-2016-06-02-191101.png)
![device-2016-06-02-191048](/uploads/a5e6def118646a02c6bcbf17e0398484/device-2016-06-02-191048.png)

Closes #409

See merge request !210

This replaces the custom layouts in the navigation drawer with a
`NavigationView` and adds a menu entry for Blogs.

A Main Blogs fragment is added that holds a `TabLayout` and a
`ViewPager`. Five tabs are already added, but they just have a single
placeholder fragment that is to be replaced by the actual fragments.

Closes #409

It does so by extending the compound view `TextAvatarView` and provides
convienient setters that take care of the required UI changes.
The new badge can also be used to indicate a problem with the forum.

Closes #408

with each other at the same time.

Closes #388

fixed sub-tree duplicate bug

Closes #422

See merge request !206

122 threaded discussions

This branch contains the complete code for the nested forums (UI & back-end).

* This branch has an optional randomized set of dummy test data, uncomment one line in ForumActivity.java and then open up any forum.


See merge request !201

Message Dependencies

This MR adds a new table to the database to hold message dependencies.
It introduces two more message states  (pending and delivered) and completely changes the validation and message delivery logic.

Since this is a **very invasive** change, please **review carefully**. It is better to catch issues now than having to debug things later. If you notice an area without tests, please let me know. I tried to have tests for all changes.

Unfortunately, this MR turned out rather large, but most of it are actually tests and you can review one commit after the other without needing to see the full changelog.

In order to reflect the new states, things that were previously true for `VALID` messages have been changed to now be true for `DELIVERED` messages. This might have changed the semantics in some places and can have unindented side-effects.

The `DatabaseComponent` was extended with methods for:
* adding dependencies
* getting dependencies and states of a message
* getting messages that depend on a message (dependents) and their states
* getting messages to be delivered (by startup hook)
* getting pending messages to be possibly delivered (by startup hook)

The `valid` column in the database was renamed to `state` along with the associated methods to better reflect its new extended meaning.

Since pending messages should not be available to clients, many database queries have been modified to only return results for delivered messages. I might have missed some. Please check carefully. Also you might want to think about how you could create arbitrarily large transactions by sending malicious messages.

Please note that the database version was bumped in this MR.

Closes #382

See merge request !198