Upgrade RxJava to version 0.19
fix #3973: RxJava periodic timer is not stopped in onPause
Added source jars for rxJava 0.19.0

- it might be necessary to close and reopen the project to make them used
crowdin: New translations
Merge pull request #3974 from rsudev/crowdin_translations

crowdin: New translations
fix #3970: crash when trying to change GC-username
Fix bulding with gradle/Android studio.

Update rx java to 0.19
Also add unfinished prototypes for the seldom used side projects.