Improve recents kill all buttons behaviour

Adding programicaly set of margin for devices without HW keys.
Also changed UI behaviour to respect stock look.
Moved RAMBAR based on new UI behaviour.

PS7: Changed ImageView into ImageButton
PS8: Remove ugly background around icon
PS12: Increased RAMBAR padding to fit new layout
PS13: Little cleanup + change tablet detection logic (from RC)

Change-Id: Ifd91e8a14d5f7eaaa05bc4958820b97ac6bf2e9c
Signed-off-by: kecinzer <kecinzer@gmail.com>
Merge "Improve recents kill all buttons behaviour" into kitkat