coplanar/calendar: Use the callback based event loading

Now that DB error can be handled anywhere we don't need to get all the
data during the setRoute() anymore. So just use the provided callback
mechanism making things a lot simpler.
coplanar/calendar: Make setRoute() synchronous again

Now that setRoute() itself doesn't do any data request no need to
return a defered anymore.
coplanar/calendar: Update the view when events are created or destroyed