Implemented frontend and backend for social networks(FaceBook) and microblogs(Twitter) and api for social networks. 

For run my code, you must have 3 android libraries:
- ActionBarSherlock
- facebook-android-sdk-3.7
- [LazyList](https://github.com/thest1/LazyList)

In this pull request I implemented frontend and backend for social networks(FaceBook) and microblogs(Twitter). For social networks I implemented api. Thanks to this further adding data sources will be simplified. 

For using this api you must implement interface  `ly.priv.mobile.api.gui.socialnetworks.ISocialNetworks` and set it with method `setISocialNetworks`.
 And  run api:
```java
FragmentTransaction transaction = getActivity().getSupportFragmentManager()
.beginTransaction();
ListUsersFragment mSListUsersActivity = new ListUsersFragment();
mSListUsersActivity.setISocialNetworks(this);
transaction.replace(R.id.container, mSListUsersActivity);
transaction.addToBackStack(null);
transaction.commit();
```
Have you made any changes to PrivlyApplications ?