Added support for experiments

.gitignore

@@ -0,0 +1 @@
+.idea/

jsend.go

@@ -73,9 +73,10 @@ const (
 )
 
 const (
-	fieldMsg    = "message"
-	fieldData   = "data"
-	fieldStatus = "status"
+	fieldMsg         = "message"
+	fieldData        = "data"
+	fieldStatus      = "status"
+	fieldExperiments = "experiments"
 )
 
 // Wrap wraps given http.ResponseWriter and returns a response object which
@@ -134,6 +135,11 @@ func (r *Response) Data(data interface{}) JResponseWriter {
 	return r.Field(fieldData, data)
 }
 
+// Data sets response's "data" field with given value.
+func (r *Response) Experiments(experiments interface{}) JResponseWriter {
+	return r.Field(fieldExperiments, experiments)
+}
+
 // Message sets response's "message" field with given value.
 func (r *Response) Message(msg string) JResponseWriter {
 	return r.Field(fieldMsg, msg)
@@ -190,6 +196,10 @@ func (r *Response) Send() (int, error) {
 		r.Data([]byte(nil))
 	}
 
+	if _, hasExperiments := r.fields[fieldExperiments]; !hasExperiments {
+		r.Experiments([]byte(nil))
+	}
+
 	j, err := json.Marshal(r.fields)
 	r.Header().Set("Content-Length", strconv.Itoa(len(j)))