fix bug in controller with undeclared variable... must have deleted it before
install omniauth and linkedin gems
add omniauth initializer
add figaro gem for env variable management
lay out new basic form path
set up functional user creation with linkedin auth
run migrations and validations to make user emails and cohort_id not null and to add fname and lname to the list of attributes
clean out old linkedin signup stuff and update TODO
add gibbon and mailchimp subscription when saving.  After destroy callback is not tested and probably doesn't work.
turn off welcome email from mailchimp subscriber
add letter opener gem for development emailing
add welcome mailer for new signups.  Note: unsubscribe on destroy tested and it works