URBNG-469: Register and login functionality
Made some of suggested changes.
Small changes
Added check for empty json in isValid method.
[URBNG-73] Completed

Finished subtasks:
- [URBNG-450] [Android] Modify server  to send selected answers
- [URBNG-451] [Android] Modify UI to interact with user in sending
choices
Sample data and naming fixes.
Basic functionality of downloading games
Merge pull request #152 from element31/android

URBNG-538: Updated game details look.
Merge branch 'android' of github.com:element31/UrbanGame into login_register
Merge remote-tracking branch 'upstream/android' into android
Naming convention changed.
Merge pull request #159 from KamilLelonek/android

[Android][URBNG-73] Completed
Made some suggested changes
Merge branch 'android' of github.com:blstream/UrbanGame into login_register
Added class to handle templated uris.
Fixed bug with null error messages.
Merge branch 'login_register' of github.com:element31/UrbanGame into download_games