rest-client-exception-bug

This application demonstrates that a WebApplicationException thrown by the REST client is not handled properly and results in the same status code being returned in the server response. The behavior is reproduced in GreetingResourceTest: when /hello is hit, GreetingResource performs a request using the REST client which gets a 400 back; at this point, the application returns a 400 but I believe it should return a 500 (there was an error while processing the request; the fact that the error happened because the application got a 400 while invoking an API is an implementation detail)