Bug Fixes For Middleware and messageType recommendation
This release contains several major bug fixes for #14 and #15.
Along with these fixed, Rabbus now recommends you do not use a messageType
properties for message producers or consumers, with the exception of the Publisher and Subscriber objects. Due to a limitation that will hopefully be addressed soon, Pub/Sub requires either a messageType or routingKey.
I also added CONTRIBUTING.md and a CODE_OF_CONDUCT.md to the project.
If you're using v0.7.0, please upgrade to v0.7.1 immediately.