[1/2] base: task utils and navigation bar

http://jira.omnirom.org/browse/OMNI-398
http://jira.omnirom.org/browse/OMNI-345

-added switch to last app as navigation ring target
-added optional kill on long press on back

PS2
much easier :)

PS3
whitespaces

Change-Id: I31f11fcd0efb90f007017fa16567e6711002ecc8