Fix uneven spacing of navigation bar buttons

* Add two dummy views to the left and right corners to
  bring the buttons nearer to the center
* This makes it easier to hit the back and recents key,
  and makes it identical to what the Sony firmware has.

It's the litte things that matter :)

Change-Id: I180ed2cf1370139f0bbadad963881b20f269e76d
Merge branch 'cm-11.0' of https://github.com/CyanogenMod/android_device_sony_togari into cd-4.4