Performance test infrastructure

I have updated the build file to run performance tests under a pt:test goal. Performance tests are denoted as having a "Benckmark" suffix.

A performance test has also been supplied that will exercise a GET request being made for an unknown handler i.e. a 500 response is returned. This test exercises most of the machinery required to handle a request and dispatch a response without Netty, networks and other handlers getting in the way. The test uses Contiperf and, as such, will output a CSV that we can use to plot commit trends in relation to performance.