Add NoContentResponse and update CreatedResponse to allow body (#385)

* Add NoContentResponse and update CreatedResponse to allow body

* Add changes

* Remove body from created

* .

* .

packages/adl-rest/lib/rest.adl

@@ -17,6 +17,10 @@ model AcceptedResponse {
   @header statusCode: 202;
 }
 
+model NoContentResponse {
+  @header statusCode: 204;
+}
+
 model MovedResponse {
   @header statusCode: 301;
   ... LocationHeader;