Converted project to Play 2.3.2-RC2

Going with a release candidate due to a bug (see comments in code)
With perfect timing Play releases 2.3.2
Merge branch 'master' of github.com:guardian/frontend into play-2.3.0

Conflicts:
	common/app/dfp/DfpAgent.scala
Merge pull request #5128 from guardian/play-2.3.0

Converted project to Play 2.3.2