Edition is now abstracted away from Site.

You no longer care about the Site (read domain) when asking for an edition.

This is part of moving us to a single domain
Merge branch 'master' of github.com:guardian/frontend into single-domain
Most dependencies on Site are now gone.

The few remaining ones will be deleted after single domain.
Merge branch 'master' of github.com:guardian/frontend into single-domain
No need for that TODO, all done
You can now change editions while on a single domain site
Merge branch 'master' of github.com:guardian/frontend into single-domain

Conflicts:
	common/app/assets/javascripts/common.js
	event/app/views/fragments/latest.scala.html
	event/app/views/fragments/storyArticle.scala.html
Merge branch 'master' of github.com:guardian/frontend into single-domain

Conflicts:
	common/app/assets/javascripts/common.js
	event/app/views/fragments/latest.scala.html
	event/app/views/fragments/storyArticle.scala.html
Merge branch 'master' of github.com:guardian/frontend into single-domain

Conflicts:
	common/app/assets/javascripts/common.js
	event/app/views/fragments/latest.scala.html
	event/app/views/fragments/storyArticle.scala.html
Merge pull request #764 from guardian/single-domain

Edition is now abstracted away from Site.