remove verification method from subscription

Before we were having subscription fetch the verification from the balanced api. This caused the subscription to be doing more work than intented. Now we can use the built in Verification::fetch instead.
move verification confirmation process to the verification model and controller

Before, confirming a verification was being handled as an update action on a subscription model. Now the form the enter is rendered through VerificationsController:edit and patches to VerificationsController:update. All the appropriate routes. Also the added benenfit of not having to rely on callbacks in the subscription model, making subscription instances much easier to work with.
add authentication to subscription, verification, and user controllers
clean up routes and controllers by removing unneccessary actions