Add 'mail' gem to Gemfile
Write unit and acceptance specs for 'welcome email is sent to a new user upon registration' user story
Create html.erb and text.erb views for welcome_email
Create UserMailer model
Add custom logic to 'create' method in registrations controller
Refactor based on Dan's feedback
Merge pull request #20 from mattThousand/user_receives_email_upon_registration

User receives email upon registration