Toggle nav bar through power menu (2/2)

- This is highly based on this commit form SlimRoms: https://github.com/SlimRoms/packages_apps_Settings/commit/30482e059fb55b9d3aa4d461a0715d77ec70776a
- Now we can toggle nav bar on/of in power menu. It's easier to use PIE.

Thanks again to @kufikugel

Codes ported and new codes from @cristianomatos

Change-Id: I63c686ebd19d3a50afe3d71de191e484208000f2