bluetooth: Materialize dialogs

Some dialogs imported from CAF are still using a Holo style, this
patch changes those to material and changes some layouts for better
usability:

1) Changes the enable dialog when something is shared via BT and it is off.
2) Changes the enabling progress dialog.
3) Removes a Toast (visible in screenshots)
4) Sets a transparent theme on the intent receiver, it's only a forwarding
   activity but it is up for enough time and shows a ugly incomplete view
   that immediately disappears.

Change-Id: Ia3f64f7d22a6486565df3035d22883e8d216dbe0

Conflicts:
	res/layout/bt_enabling_progress.xml
	res/layout/confirm_dialog.xml