display: Make advanced settings a category

This was a separate screen but it's too empty for that, let's make
it a category like in CM11 for now. If it ever becomes a separate
screen it needs its own fragment so that navigation is possible
via actionbar.

Change-Id: I4b1f3e78a013412d5e39847683ca622dc76b9fa1
Launch SuperSU from Settings
[2/2] Profile: Screen timeout
[2/2] Battery light: 100% charged level