Added login screen, nav drawer, swipe to refresh, many dialogs, prettier colors & styles

- Added a start screen with server version check and login form
- Added a navigation drawer for easy navigation
- Added swipe to refresh
- Changed colors of action bar and input fields (colorPrimary,
colorPrimaryDark, colorAccent, colorAccent2)
- Added dialog to inform when debug mode is enabled
- Added dialog for invalid login
- Added dialogs for server & internet connection errors
- Added german translations
Added missing german translations
Increased version code to 2 and name to 0.0.1
Built release apk version 0.0.1