1. GroupsFragment has been created with create and read functionality
2. New Server API methods (addGroup, getGroups), also their mirrors in ServiceHelper have been added
3. Database scheme has been changed (id and remote_id fields)
4. Custom checkable cursor adapter has been implemented. It's based on the idea of remote_id field
5. New usefull functions in ProviderUpdater (insertTempRow, persistRow, updateRows have been remade)
6. New status bar with aniamted statuses
6. Less important improvements has nave been done

// TODO:
1. Implement update and delete functions for groups
2. Improve ApiServiceHelper for performing parallel api requests