* Changed TestCacheSupervisor for easier use of the many callbacks
* Adapted tests for new callbacks
* GroupBaseActivity: Added sync menu command
* Preferences: Added option to enable/disable offline caching
* App: don't lock database when user wants to reload. This is done in PasswordActivity and should be done there after the password was filled into the pw field
* CheckDatabaseForChanges.cs: used when syncing a non-cached database
- keepass2android: UI stuff only
- Kp2aBusinessLogic: Password-Database related algorithms (even though tied to android, no UI required here)
Removed dependencies of logic layer to static Application, Resource class or other UI stuff
Added MonoDroidUnitTesting (not yet used, will be used for testing logic layer)