base: Add a key combo to start/stop video recording

Press volume up and power to start recording a video of your screen.
Press this key combo again to stop it.

Change-Id: Id0b13ba1092a1d6e0bf7bff5f14d89764cdf370c
Signed-off-by: ChampionSwimmer <championswimmer@aokp.co>

Conflicts:
	packages/SystemUI/res/values/custom_strings.xml

Conflicts:

	packages/SystemUI/res/values/strings_custom.xml
	packages/SystemUI/src/com/android/systemui/omni/screenrecord/GlobalScreenrecord.java