Fix 1998 : OData-EntityId header not returned for 204 Patch Responses

If client sends a request with Prefer: return=minimal, and then service
may return an http status code 204 without response content, and also add
a response header OData-EntityId.
"if the service applies a return=minimal preference. In this case, the
response body MUST be empty."

Change Prefer return parameter to: return=representation, and return=minimal
For a response to a create (post/patch/put) operation, add OData-EntityId header,
if response is with status code: NoContent