Allow simple delete

[afandian]

The HTTP PUT functionality currently allows an Event to be updated, including setting the 'updated' flag to 'edited' or 'deleted'. When this happens, the whole Event must be sent again, with modifications, and it is updated in its entirety. This is because when we delete (for example for Twitter compliance reasons) we only need to remove the Twitter-sensitive data and can leave the rest behind.

In some cases a consumer may wish to simply mark an Event as being deleted without modifying it. In this case, all that is required is the updated_reason.

Implement an HTTP DELETE endpoint that is able to accept only an updated_reason field, and will merge the updated, updated_date and updated_reason with the previous Event's data.