Only send confirmation email to volunteers

https://www.pivotaltracker.com/story/show/41278297
Rsvp mailer: Refactor volunteer_confirmation

per tjgrathwell's comments in
https://github.com/railsbridge/bridge_troll/pull/143
Add some detail about using MailCatcher for email
Add some detail about using MailCatcher for email
Rsvp mailer: render the body

I was using some fancy footwork to send confirmations only to
volunteers, and that interfered with Rails' default mailer template
nomenclature.  Pointed the mailer to the right template, added some
tests to catch this in the future. Added location to the event
factory to enable tests.
Merge branch 'rsvp-confirmation-mailer' of https://github.com/k-stewart/bridge_troll into k-stewart-rsvp-confirmation-mailer
Improve confirmation email template
Use HTTPS rubygems
Merge pull request #146 from fionatay/https_rubygems

Use HTTPS rubygems
user sees volunteer and learn buttons on home page when logged out
Add rake task for confirmation email sending
Ditch .rvmrc

* Use .ruby-version and .ruby-gemset instead
* Maybe then rvm will love me :(
Merge branch 'user-sees-buttons' of https://github.com/treble37/bridge_troll into treble37-user-sees-buttons
Merge pull request #148 from ohrite/modernize-ruby-version-and-gemset

Ditch .rvmrc
Purge .rvmrc from the readme and mention rbenv
Refactor bootstrap script for readability
Merge branch 'refactor-bootstrap-script' of https://github.com/ohrite/bridge_troll into ohrite-refactor-bootstrap-script
Make ruby-version work with rbenv
Revised version of Learn/Vol buttons for signed out users.

* Show the 'Sign In' form as a modal instead of going to another page
* Show the Learn/Volunteer buttons in their own "RSVP" column rather
  than hijacking the Location column

This required some somewhat shady js layered on top of bootstrap's
  rather anemic modal. Check out sign_in.js.coffee for some fun.
Merge branch 'ruby-version' of https://github.com/fionatay/bridge_troll into fionatay-ruby-version