Make Telegram code FOSS friendly

Hi,

Current Telegram code depends on non-free services and contains binary blobs, so it doesn't qualify as Free Software attending to some criteria. These changes try to address this issue:

- Remove binary blobs from repo.
- Create two Gradle flavours, "standard" and "foss". The first one builds Telegram with Google Play Services and HockeyAppDB, while the second removes those dependencies and their related functionality (Location sharing and updates).

If you don't feel comfortable with those changes "as is", but would rather accept an alternative disposition, please let me know what would you change and I'll try to comply your requirements.

Thanks!