Buttons: Prevent toggling disable hardware keys too quickly

* Apparently the phone window manager _really_ doesn't like it when you
  do toggle this too quickly.

Change-Id: I936c6554927ffcdc7c78edaf25f71aedba497ac8
Merge "Buttons: Prevent toggling disable hardware keys too quickly" into cm-11.0
Merge remote-tracking branch 'cm/cm-11.0' into HEAD

Conflicts:
	src/com/android/settings/cyanogenmod/ButtonSettings.java

Change-Id: Idc77ba900c14e62117f8506afa47e1bdfc0685a7