added confirmation to subscription
moved subscription methods into the subscription controller
updated subscription to require confirmation - email built
added check to notification sender that unconfirmed subscriptions will not receive emails
added tests around the confirmation endpoint
rewrote unsubscribe to use a form and post / get request, and added confirm page for manually entering confirmation code
added plivo as a dependency
set up plivo to send SMS messages for both confirmation and for notifications
added plivo details to the travis yml file
updated subscription with validations and an as_params method
updated pet with many scopes and time scopable concern
updated the subscription form to be more friendly and handle confirmation easily
Merge branch 'plivo' into confirmation
Merge branch 'confirmation'