Renamed YaniActivity -> MainActivity

- Added a new package namespace yani.activity
- Renamed the initial activity (Yani) to Main activity
Add a clean interface for activity -> section communication.

Add a FragmentEventsListener interface which is used to notify of any
events within the section fragments (currently only onAttach).
Restore section fragments when available.

- Restore the section fragments when they're available within the fragment
manager.

- NavigationDrawerFragment now sends both the old position and new
  position to the listener, which helps in figuring out if the fragment
  needs to be reused from the fragment manager.
Disable toasts for network broadcast events.
Rename package com.github.tuxdude -> org.tuxdude .
Increase the mininmum SDK version to android-17.

Child Fragment Managers are only supported with android-17 and above, so
bump the minSdkVersion to android-17.