Update delete action behavior and JSON format output (#1155)

This PR changes delete behavior:

* On success, a 204 is returned rather than a 200 with an empty JSON object
* The CLI now passes through the 404 error if encountered instead of swallowing it

It also updates formatting for JSON to use the response body, which means that the item (or items) in the JSON format are actually the format across the wire, instead of being reinterpreted by unmarshaling into the Go SDK and then remarshaling.

api/scopes/scope.gen.go

@@ -50,6 +50,11 @@ type ScopeDeleteResult struct {
 	response *api.Response
 }
 
+// GetItem will always be nil for ScopeDeleteResult
+func (n ScopeDeleteResult) GetItem() interface{} {
+	return nil
+}
+
 func (n ScopeDeleteResult) GetResponse() *api.Response {
 	return n.response
 }