Attendee mis/counts

In the event that user_attend table ends up with multiple references to the same event and user id.

I found that the users are:

* miss counted on event row views, and,
* on an event view, when you press show to show the attendee list, it shows a non distinct list. (The count here is correct with no fix to apply)

I've patched the queries.

(Apologies for my text editor automatically lopping off extra spaces at the end of lines)

@TODO: Patch the (V2.1) API so that on POST attend the API checks if the user/event reference exists already