Add padding to join contact list view

Several changes are involved:
1. Add padding to all the contact list views of ContactSelectionActivity so
they can be contained in a centered card in sw600dp-land and sw720dp mode.
2. Make the tab indicator thicker on tablets.
3. Make tab text size, frequently contacted title text size, list item text
size and list item line space bigger on tablet.

Bug:16553819
Bug:17132856
Bug:17157006

Change-Id: I5f5a53e33f8ea090573edb1c7f23ebac7260190d