Support for JAX-RS Application subclassing with configuration in web.xml

As described in https://docs.jboss.org/author/display/AS7/JAX-RS+Reference+Guide, the plugin should support the following use case:

Subclassing javax.ws.rs.core.Application and using web.xml
If you do not wish to use @ApplicationPath but still need to subclass Application you can set up the JAX-RS mapping in web.xml:

public class MyApplication extends Application {
}

<servlet-mapping>
   <servlet-name>com.acme.MyApplication</servlet-name>
   <url-pattern>/hello/*</url-pattern>
</servlet-mapping>