add unsubscribe_from_gauge method
add unsubscribe_from_gauge to routes.
add subscribed? method to user model
modify river show view to toggle subscribe and unsubscribe depending on status
modify river index view to toggle subscribe and unsubscribe depending on status
bug fix. subscribing and unsubscribing now work as expected.
Merge pull request #25 from studiostark/master

Can now subscribe and unsubscribe. Buttons display correctly depending on subscription status.