Twitter: Added some logic for the friends endpoint
Facebook: Renamed property "ReturnUri" to "RedirectUri" to follow Facebook and OAuth 2.0 lingo
Instagram: Renamed property "ReturnUri" to "RedirectUri" to follow Instagram and OAuth 2.0 lingo
Twitter: Lots of new logic for the Twitter service

- More methods are now supported in the friends endpoint
- Added support for some methods in the followers endpoint
- Added support for search methods in the users endpoint
- Added support for more timeline related methods in the statuses endpoint
- Improved the TwitterUser object with better support for entities