Remove RSVP/unRSVP forms from our page, replace with handlebars

[shecking]

We don't need either RSVP or unRSVP forms as they currently exist (enter and submit the id, which triggers the RSVP actions).

Using handlebars, these should be turned into buttons that trigger the same event as these forms.

Buttons should be hidden and shown at appropriate times; e.g. RSVP shown/unRSVP hidden when a user IS NOT RSVPd, RSVP hidden/unRSVP shown when a user IS RSVPd.