Add back blacklist settings.

Change-Id: Iae35717acfa9af4da75c07d24352acf981d19fc7

Improve translatability of summaries.

Change-Id: I362b335cbe219d6e371a458c9d50fcd66bdf19fe

Settings: Alert user when they attempt to add an invalid number to BL.

  - BlacklistProvider will reject numbers that aren't valid, silently. So instead of
  resuming to a blank screen, we should alert the user that the number they attempted to
  add is invalid by utilizing BlacklistUtils#addOrUpdate method.

Change-Id: I1ca32427baad41c1c9379e18046e6ca7937b6d32

Add missing blacklist xxhdpi drawables.

Change-Id: I327f408ff344e9358c479cf5fe9dc341918511b2

Blacklist: Fix launching blacklist settings

Change-Id: I0043503e6ac0d3536941394ee5057001b72f9114

Settings : Launch only contacts picker for blacklist entry

Change-Id: I266d1ad7f1aab745728b33490268cb197188f2b3