* generate a RestResourceRoot with a string constant holding the jax-rs resource root to be used in the @ApplicationPath annotation to make it easier for people, who want to write their own jax-rs Application class
* build and update samples as per PR guide
* renamed introduced constant from ROOT to APPLICATION_PATH to make its use more obvious
* Use contextPath variable for RestApplication templates
* Update generated RestApplication.java files, as they are skipped by default otherwise
* Update Petstore sample for jaxrs so that CIs can verify the change
* sample server projects "jaxrs-spec", "jaxrs-spec-interface", and "jaxrs-spec-interface-response" should be tested
* update jax-rs api to 2.1, in which @PATCH annotation is available
add jackson annotation dependency
* add joda-time to dependency
* modify mustache template to add @JsonCreate, @JsonValue import
* fix return type of enum value() method
* add InputStream import
* Attachment class is in apache cxf. spec should not depend on it
* re-generate sample jaxrs-spec, jaxrs-spec-interface, and jaxrs-spec-interface-response
