Set the required fields when not specified while adding events through ReST

Certain event attributes like the event time are required when creating events.

It would be useful if the ReST end-point for create events can check if the required fields are populated or not, and in case they are not populated, set reasonable defaults.

The event time has to be specified in GMT and the format is not conventional. If someone wants to add an event through ReST, it is obvious (at least to me) that the time should be the time when the request is executed.