Prevent audio players starting on startup.

Previously, (at least) Apollo was started on startup (in that it
appeared in the notification bar) because it listens to the AUDIO_BECOMING_NOISY
intent to silence itself in that case. This intent is broadcast by
AudioService when there's a user switch to silence any potential audio
players for the old user. As the system also sends around a
USER_SWITCHED intent on startup, this led to the aforementioned player
startup.
As the intent of AudioService was to act on a user backgrounding anyway,
send out AUDIO_BECOMING_NOISY as reaction to a USER_BACKGROUND intent
instead of the USER_SWITCHED intent.

Change-Id: Iba35844a1274c9dd195f104068304e6a7ffa809e
Keyguard: remove duplicated code

Patchset 2: fixed whitespace error
Patchset 3: a few more tiny changes
Patchset 4: some code moving, removing an unnecessary member
Patchset 5: make toggleSilentMode() a bit easier to read
Patchset 6: revert most of the cleanup
Patchset 7: fix syntax error
Patchset 8: fixes pointed out by Danny Baumann

Change-Id: I4e5f8c92b223c1260891472dbf807d5ff53e5721
SystemUI QuickSettings: Allow more off-status localizations

Create strings for NFC off and Sync off so that they can be localized
appropriately.

This is a continuation of: http://review.cyanogenmod.org/#/c/30327/

Change-Id: I070310868147af84b10d15c7d872f6d43120434b
SystemUI: highlight quick settings and notification clear buttons

Actually make use of the drawables bestowed upon us by the Google

Change-Id: I54ed68cf529eec0a0b76e9e35599d70a7d38f686