add Voice Wakeup switch

 * Requires CYNGN package to do the actual work.

Change-Id: I1c129adf1104dd95d3afb76224af4c9ba2b5db96

Settings: Fix build error after 70f60fa6

Change-Id: I6e83391e02fd0e6dc0d050d5a9a7dd6816a1910b

Settings: Update voice wakeup icon

Change-Id: Ie75e8a41f69097384f3d2eec2503ae4cfe6a2a0b

Settings: Hide voice wakeup category when package isn't present

Change-Id: I33a34a56b3a1d1ad04b07bde4aec6c3c230fc297

Add metrics category for VoiceWakeup

Change-Id: I101729d964f9aca032a9899917b59a035c299ecf