Moved to Nett 4.0.7-final

We'd been working off Beta3 and a number of things had changed
since then. This updates the dependency to 4.0.7 final and
makes the necessary changes in our code.
Bug fix, multiple expections from pipeline

Forgot to change this. It would throw a NoSuchElementException if
the timeout handler had already been removed.
Merge pull request #274 from basho/update-to-netty-4-final

Moved to Netty 4.0.7-final