inform volunteer_opportunity people when someone signs up for a volunteer choice
change to use the registrant's bib_number is the url
fix specs failing due to auto-setting bib_number
add ability for user to sign up for volunteer opportunities
add google analytics tracking id
replace application layout with haml
clean up current_user vs user_signed_in?
remove mixpanel, and GoogleAnalytics to readme
refactor registrant#index to break it apart