SystemUI: Separate system bar BGs for themes

This commit separates the navigation bar background colors from the
status bar background colors which allows more modular theme-ability.
Backwards compatibility for the old system bar values is still
preserved, but the new values are to be prioritized.

Thanks to Arz Bhatia for the suggestion.

Change-Id: Ibe579d16ea35ca5bdcfe9f98143c3f91cd24900f
Framework: Make the dialog divider color themeable

The holo blue color might not be suitable for some themes. This commit
swaps out the background of all titleDivider elements to use another
resource. This has no difference from the perspective of the user of a
"stock" build but this is huge for theme users.

Thanks to Arz Bhatia for the suggestion.

Change-Id: Icb917220accac3ad38770067120a7b1be894961a
[2/2] Add option to change size of QS ribbon bar

PS2: Use narrow for 2nd size and decrease margins for smaller tiles
PS3: Remove trailing WS + rebase
PS4: Rebase and fix unchanged dimen use
PS5: Fix renamed dimen missing
PS6: Change narrow to automatic and move applying of settings down
PS7: Make small be narrow instead. "Small" is actually Auto (Narrow)
PS8: Use measuredWidth and modify HorScrollView, otherwise layout changes will be ignored
     (Orientation switches were a big problem)

Change-Id: I6dbe2d165398a8142e024db827208dc778003431