NavigationBar : Customization

Allows user to customize navigation bar.

Features :
 - Choose from 1-6 # of buttons
 - Re-arrange / assign buttons

Patchset 1  : Initial commit (No support for Nexus 7)
Patchset 2  : Same as patchset 1
Patchset 3  : Update recentPanel on configurationChange
Patchset 4  : Rebase
Patchset 5  : Add n7 support
Patchset 6  : Fix n7 layout issues
Patchset 7  : Theme change fixes (Update referenced resources on demand)
              Update a few deprecated api calls
Patchset 8  : Disable google now ring in edit mode
Patchset 9  : Fix n7 lowLight alignment issues
Patchset 10 : Fix ordering/button disappearing issues
Patchset 11 : Rework orientation logic (Fixes the small back button issue)
Patchset 12 : Rebase
Patchset 13 : Fixed back_ime button in xhdpi (and others res) landscape

Change-Id: Idc9f5f401f15d207504e49de47666bb5510a06ca