Added a MemcachedAction

going to try run this a bit to see what happens
Merge branch 'master' of github.com:guardian/frontend into memcached

Conflicts:
	common/app/common/akka.scala
Merge branch 'master' of github.com:guardian/frontend into memcached

Conflicts:
	common/app/common/akka.scala
Make MemcachedAction configurable accross stages
Merge branch 'master' of github.com:guardian/frontend into memcached
Switched off by default
Done the TODO...
Dont' need Play cache
Merge branch 'master' of github.com:guardian/frontend into memcached
`import scala.Some` mid-packery
Merge pull request #3733 from guardian/memcached

Memcached Test