added support for JAX-RS 2.0 async resources
Merge branch 'x-async-response' into x-oa-build

Conflicts:
	core/src/main/java/org/raml/jaxrs/codegen/core/Configuration.java
	maven-plugin/src/main/java/org/raml/jaxrs/codegen/maven/RamlJaxrsCodegenMojo.java