General Tidy Up and Code Review

[mikel]

OK, there is more to do here... but in a nutshell:

Large scale clean up to reduce complexity and improve on single responsibility principle

• Remove any responsibility of the receipient from Auth Token
• Remove recipient_email from AuthToken - no longer needed
• Greatly simplify AuthTokenController
• Removing generating temporary auth_tokens, not needed
• Remove need AuthToken#generate, rely on before_validation AuthToken#set_defaults method
• Move validation from auth_token_controller into models/auth_token
• Move session[:validated_email] into a set of helper methods
• Rename ApplicationController#check_session into the consistent session helper methods
• Simplify and split :open, :limited and :closed system checks into auth_token and secret
• Require both the secret UUID and correct key to show a secret (helps prevent fishing)
• Validate the recipients email when they click the link and the secret key is correct
• Move validation from secret_controller into models/secret
• Adds reply_to on email per issue #31 (snuck in there)
• Remove SecretService.encrypt_existing_secret
• Remove need to pass around request host, use _url route helper in mailers instead
• Improve feedback to user with better error messages
• Remove error trace dump from error message, report to Bugsnag instead
• Remove ability (and need) to edit secrets at all
  • Note, we could add this back once we have validated users
• Some prep to migrate to UUIDs as IDs on models
• Remove unused ApplicationController#development method
• Adding foreman, byebug and binding of caller, removing old pry