Option to validate upon #confirm!

Allow to ensure valid upon confirming.
We might want to consider confirmation status in validations. For example, maybe we want to require certain fields upon confirmation, but not at registration.

lib/devise/models/confirmable.rb

@@ -56,7 +56,7 @@ def self.required_fields(klass)
       # Confirm a user by setting it's confirmed_at to actual time. If the user
       # is already confirmed, add an error to email field. If the user is invalid
       # add errors
-      def confirm!
+      def confirm!(ensure_valid=false)
         pending_any_confirmation do
           if confirmation_period_expired?
             self.errors.add(:email, :confirmation_period_expired,
@@ -75,7 +75,7 @@ def confirm!
             # We need to validate in such cases to enforce e-mail uniqueness
             save(validate: true)
           else
-            save(validate: false)
+            save(validate: ensure_valid)
           end
 
           after_confirmation if saved