Changes to support new screen cast settings screen.

Fixed the Preference ordering code to consider the case where
two preferences might have the same order.  In that case, it
falls back on the title to disambiguate.  Previous behavior was
undefined (and technically not stable).

Expose the wifi display device address.

Perform wifi display scans every 10 seconds instead of every 15
to improve reponsiveness.

Make sure to define routes for wifi displays that we are connecting
to even if they are not yet paired.  Simplified the logic for
adding and removing these routes to avoid possibly getting out
of sync and leaving stale routes behind.

Fix wifi display notification icon.

Bug: 11257292
Change-Id: I8ac15fb17d83758c0bdce80399e12723c367b83c