Add bottom bar UI for photo page

Bug: 7050303
Bug: 7170148
Pulled the handling of the display of the edit (FX) button
out into a separate file and put in the groundwork for
supporting multiple buttons within a container along the
bottom of the screen and managing their display as well as
animating them in and out. Also added a button for launching
the panorama viewer when appropriate

Change-Id: Iee3083e0693ef3c1f55264b922f02b9a702d2103