SystemUI: Add option to hide signal bars

Patch set 1: Bring back option from jb
Patch set 2: Update for Settings.AOKP
Patch set 3: Add needed dependency

Change-Id: I93e78d48412e1a82a271d002066fa8a4c0101d16
Signed-off-by: Rohan Mathur <rohanmathur34@gmail.com>