Do not show Sessions section in RSVP form for single-session events.

Users are automatically RSVP'd to the single existing session for these events.
Destroy event session RSVPs when event sessions are destroyed
Add confirm to unvolunteer button
Update README.markdown
Remove declared widths on .container so they have responsive bootstrap sizes

(940px, 1170px, etc depending on screen width)
Organizers can 'un-checkin' volunteers from sessions
Admins can access organizer console and do organizer things
Allow meetup association even for users with no meetup RSVPs

Add WestEd workshop to historical workshops data
confirm admin seed
added gravitars to users
Merge branch 'seed-admins' of https://github.com/Dreyfuzz/bridge_troll into Dreyfuzz-seed-admins
Merge branch 'user-gravatars' of https://github.com/Dreyfuzz/bridge_troll into Dreyfuzz-user-gravatars
Behave better when importing meetup events with already-associated bridgetroll users
Don't include Bootstrap JS. It traps middle clicks (somehow.)
Don't import student RSVPs for waitlisted students

Delete imported RSVPs that were created for waitlisted students.
Upgrade shoulda-matchers to 2.0.0

Fixes #133