Ticket #252 (defect)

Need xml output inside <event><subscription>... to properly determine where an event is coming from in the user client. Currently in the single event and list views we provide links to manage the underlying subscription for subscribed public calendars. To be able to do this for other user calendars, we need to see who owns the event's container (calendar collection).

Currently we test on event ownership which is not adequate; for example, if I add an event to another user's calendar to which I am subscribed, I should get the "subscription" link even though I own the event. The other user should not get the link, even though she doesn't own it -- because it's in the calendar she owns.