need better definition of 'dev' release

[dougfort]

@chrisbsmith
@tilleryd
@justincely

Attempted to do this

The version v1.2.0-dev.1 was treated as a production release (since it didn't end in 'dev')

I recommend this package for semantic versioning.

[tilleryd]

I think we just need to update Circle CI config to be more inclusive. Our naming conventions for the tags can be defined as we learn what makes the most sense for us.