Initial chat rooms UI
Single chat UI
Fix .gitignore issues

The repository already contained binary files which should have
been ignored.  Those are now removed.

The updated .gitignore file is adapted for Android projects.
Remove R.java files
Ignore files created by jimu Mirror (App for live previews of Android layouts)
REST Client implementation
Add most recent developers
Adjust ChatRoom POJO
Add ChatMember POJO
Add Chat terms dialog
Join members and join chat room
Send message
Retrieve message history
Add a class implementing a convenient API for signing strings

The class requires that a ``PrivateKey`` parameter is injected
at construction-time.
Merge pull request #1 from janapejic/feature/crypto-signature-generator

Crypto Signature Generator
Send message tweaks
AWS server
Key generation and message signing
Improving Log messages
GCM library and initial setup