Super block yield

[sgwilym]

I often find myself wanting to make small additions to the RegistrationsController (such as adding a role to a just-created User), but find overriding the entire controller a little bit overkill when I simply want to add behaviour.

In vanilla Devise you can make a controller that inherits from RegistrationsController, override the method and simply pass a block to super like this:

def create
  super do |resource|
    resource.add_role :cool_user
  end
end

Which I think is ideal for small additions like these. This PR implements block yielding in RegistrationsController (and though it could easily be extended to the other controllers, I thought I'd see what you make of this before going the whole hog on this).

And sorry if the tests are a little gross looking — I'm used to Rspec!

[lynndylanhurley]

Fantastic PR @sgwilym! The tests look great!

| think this is definitely an improvement. Would you be interested in extending this behavior to the other controllers as well?

[sgwilym]

Thanks! 😄 And sure thing. I'll scrape a little time together soon to get all the controllers all blocked up.