Add group member selection to ContentSelectionActivity (1/2)

* The GroupMemberPickListAdapter queries RawContacts to get
  the list of potential group members
* The raw contact IDs of existing group members are passed
  in to the pick fragment and these are filtered out of
  results by a CursorWrapper.
* Since we can't get the contact photo ID and contact lookup
  URI from the RawContacts query, these are also provided
  by the CursorWrapper.
* Finally, we move the current search to add contact to group
  functionality in place behind the ActionBar search icon,
  moved to the overflow menu.

Bug 28707265
Bug 18641067

Change-Id: Ifde5446e8ce9c0ed27cd2f98fd704ca669c45f59