simplifying response branches in MCAnswersController
Adds r-l-a
rm Back to Sequence button from activity TOC

[#58099020]

https://www.pivotaltracker.com/story/show/58099020
This looks like a big commit, but it's just adding module Embeddable.

git diff made a mess of things, but the change is small.
The file used to read:

class Embeddable::ImageQuestionAnswer < ActiveRecord
  include Answer
  …
end

But now it goes like this:

module Embeddable
  class ImageQuestionAnswer < ActiveRecord
	include Answer
    …
  end
end
config.ru : Use non-dev heroku shutterbug snapshot app.
This test needs to be looked at again.  Its not clear what its testing.