Support metrics for Vert.x

Signed-off-by: nscavell <nick.scavelli@gmail.com>
Merge branch 'metrics-squashed' of github.com:nscavell/vert.x into nscavell-metrics-squashed
Merge pull request #933 from vietj/master

Rxification cont
Merged and fixed new metrics SPI
Merged in new Metrics SPI stuff
Disabled all ssl protocols apart from TLSv1.1 and TLSv1.2 due to POODLE vulnerability
When setting a null handler on the MesssageConsumer, the register method should set registered flag to false otherwise registration won't effectively happen

Signed-off-by: Julien Viet <julien@julienviet.com>