This update resolves the following issues:
* [2 buildsys.task.state.change: None is not of type 'integer' ](https://github.com/fedora-infra/koji-fedoramessaging-messages/issues/6)
* [3 buildsys.task.state.change: 'Scratch image build results in: /mnt/koji/work/tasks/9833/97319833' is not of type 'null'](https://github.com/fedora-infra/koji-fedoramessaging-messages/issues/6)
* [4 The id property is reserved in Fedora Messaging](https://github.com/fedora-infra/koji-fedoramessaging-messages/issues/6)
* [5 rpm.sign message summary returns build NVR, rather than the rpm NVR](https://github.com/fedora-infra/koji-fedoramessaging-messages/issues/6)
* [6 make tag / untag messages more informative](https://github.com/fedora-infra/koji-fedoramessaging-messages/issues/6)