Updates and refactoring, read comment

- Reintegrated Settings via Fragment + Library = No hack anymore via visibility!
- Implemented In-App language switching from DE to EN
- Refactored ActivityMain to Controller and made a lot of the methods static for direct reference, also avoids some crashes because of Null pointers!
- Implemented User-Model (not tested yet as userdata is not fetched)
- Fixed a few NullPointers
- Turning/Rotation now also works in Mensadetails


- NOTE: I forgot to remove the support fragment library from the libs!!! It's not necessary, I integrated it into the app via a package! Just remove it!
- NOTE: @Theo: There will soon be a new field "votes" for a menu (the amount of people voted), can you add this to the database? Also see my issue about database and empty data!