Make compatible with resteasy 3

This Pull Request attempts to address https://issues.jboss.org/browse/HORNETQ-1255.

(Or at least, it does the minimum required work to be compatible with Resteasy 3.  It does not go as far as it could, upgrading to the jax-rs 2 client API and such.  It continues to use now-deprecated Resteasy-specific classes)