New stacked RSSI icons.

The signal strength, network type & flow indicator, and
battery have all been moved out of the policy and into the
status bar implementation itself, mirroring the change on
tablets. This means that they no longer use status bar icon
slots but instead are bespoke layouts and views.

GPS has also been removed and will return as a notification
(again, as was done in the Honeycomb tablet UI).

Bug: 4691638
Change-Id: I60df4871209b64209bfc5b3bf398651cc2e77b24