FW Ribbons Swipe ribbons seperated && logic adjust for navbar

If you have an enabled navbar weither by default or user seleted
the bottom ribbon has not been available. If the user manually
hides the navbar I will allwo them to use the bottom ribbon.
They can also long press the hidden navbar handle to get the
bottom ribbon.

This also makes the left right and bottom their own ribbons.

Change-Id: Icba9c4ec510149bef74382a3bf59fd79b3ef87c4
Add method to PowerManager that allows querying the lowest possible
brightness.

Used by the auto-brightness adjustment to adjust the sliders.

Change-Id: Idb58fd86dee1a053fe858291be6c9b3169ac4247