Lets the device use a timer.
Start the timer and call the callback when the timer has run.
Rho::Timer.start(interval_milliseconds, callback_url, callback_data)
Refer to timer in device capabilities for an example.
||Duration of timer in milliseconds.|
||callback to call at end of timer duration.|
||data for callback.|
Stop the timer by callback.
||the callback_url for this timer; stopped by this method.|