Bug 1024588 - Turn off useragent updates for tests to avoid hitting the network. r=jmaher, a=test-only
Bug 1009157 - Ensure that we can receive BT enable/disabled events in marionette test every times. r=echou, a=test-only

Ensures that we can always receive that "enabled"/"disabled" event by
installing the event handler *before* we ever enable/disable Bluetooth. Or
we might just miss those events and get a timeout error.