Netty pipeline needs an executionHandler

When making remote actor calls from an action (which runs on a Netty thread), Netty will throw an exception if that remote message send triggers the creation of a new Akka remote connection. The solution is to use an executionHandler in the netty pipeline, which I believe was done in Play 2.0 (fixing this very same bug). Why was the fix removed in 2.1?

Originally reported by @rkuhn.
@gissues:{"order":93.75,"status":"inprogress"}