Support of non-persistent entities

[joelvdgraaf]

Not always the appointments are in the database because of real-time aggregations which is pushed to non-persistent entities. Please change the Calendar definition XML that the 'eventEntity' and 'contextEntity' are allowed for non-persistent entities.
Locally I've changed it and the widget (javascript) already works with non-persistent entities, but you as developer must keep in mind of the context.

calendar.zip