WhisperPush: change appearence to Holo

Be consistent with Settings look.

Also enabled the action bar label to go back.

Change-Id: I8ceb8950cab9d286056048b0eeb2c3829bdadb9b
Signed-off-by: Roman Birg <roman@cyngn.com>
(cherry picked from commit 5c4408bf0e1faaa3442c2f94135badb11be62565)