Add UI to manage blocked numbers.

TESTING/Functionality=
 - Adding empty not allowed.
 - Rotation: dialogs/general UI.
 - Adding same number ignored.
 - Non-primary users not allowed to manage blocked numbers.
 - Material ripple for delete button.
 - Action bar back button exit activity.
 - Prevent EditText from stealing focus so talk-back starts
   from the beginning.
 - Talk back allow user to read row by row in list view.

There are two things left that I will do in a follow-up:
 - Alert Dialog Theme.
 - Add some validation for the user input

Screenshots: https://drive.google.com/a/google.com/folderview?id=0ByV4lfyID02GTGV1QWRTOGlKWTQ&usp=sharing
Bug: 26917087
Change-Id: If390d863f40162e12b0bd5d06b8bfccaa7fad5b2