Add support in StatusBarManager for disabling ticker text.

The new flag, DISABLE_NOTIFICATION_TICKER, will be used by
the car dock app (in conjunction with DISABLE_EXPAND) to
minimize distractions to the driver.

It may also be used by the secure lockscreen to avoid
leaking personal information when the screen is on but the
device is locked (e.g. when the desk dock app is running).

Change-Id: Ibc8efde7da7501767163ae0a75f7c369b824e2a2