Very simple clientside Aus edition.

Based on our preference framework it modifies links to the network front if you have opted into AUS.
Merge branch 'master' of github.com:guardian/frontend into australia
Better handling of multiple edition links on the same page
Merge branch 'master' into australia

Conflicts:
	common/app/assets/javascripts/bootstraps/common.js
	common/app/conf/switches.scala
	common/app/views/fragments/sections.scala.html
Fixing tests
Merge pull request #837 from guardian/australia

Australia edition switching