updated realtime form validator with more human friendly message and added more tests

apis/realtime.go

@@ -161,6 +161,7 @@ type realtimeSubscribeForm struct {
 func (form *realtimeSubscribeForm) validate() error {
 	return validation.ValidateStruct(form,
 		validation.Field(&form.ClientId, validation.Required, validation.Length(1, 255)),
+		validation.Field(&form.Subscriptions, validation.Length(0, 1000)),
 	)
 }