Fix 6238404: Changed deleteGallery and deleteTempGallery to use broadcasts

Previously since these were starting an activity, if it was called from
outside an activity (for example when calling resetPassword() in
DevicePolicyManager) it throws a run time exception.  Since these don't
need UI, they have been changed to be broadcasts.

Change-Id: Id87e3dc868a01f0eed901e8e8007f91f74cd51fe