Extra views integration

So this patch includes all the extra views integration work we did.

It provides fields for the two extra timestamps we added, as in issue 547990
http://drupal.org/node/547990

It also 'fixes' the rsvp total invites field, seemed to be providing the wrong data before, now provides the total number of invitees rather than the total number of rsvp objects.

It provides a relationship for the rsvp invitation hash, so you can now use an argument from the invitation url, and use that to filter to the particular rsvp object. So for example you can now show a views block of who else is coming on the invitation page.

We also added a few fields which contain links to the other rsvp pages, and invitee message/remove links.

There is also a field which gives a stripped down version of the user email address, so you can give some information about who else is attending without exposing full email addresses.