RSVP: Add 'choose adventure' page
Sessions: Allow for saving of RSVP data

Our cache invalidation on the session didn't
know about rsvp data.
RSVP: Save data in the server-side session
RSVP: Rework rsvp-layout block; inject session

Inject the server-side session into an Angular
value service.

And add one more layer of jade templates for the
RSVP section.