v0.9.0

This is planned to be the last pre-1.0.0 release of nimbus. This release brings two main changes as well as several code quality improvements and minor updates.

• #15
• #21

v0.8.0

First nimbus release. This basically represents the nimbus code base as it was when it was extracted from the cumulus repository with just a few cleanups. Future releases will make nimbus better stand on its own and have better notes.

For some history of nimbus and its life in the cumulus repo see: paritytech/cumulus#429