0.4.1 Release

Merge pull request slack-samples#64 from jammons/plugin_refactor

Update the version to avoid conflict with existing version

Merge pull request slack-samples#60 from slackhq/yasumoto-final-windo…

…ws-fix

Fix up another unix-path-ism

Merge pull request slack-samples#46 from jammons/master

Add tests and bugfix for b'' messages appearing in python3.

Merge pull request slack-samples#42 from jammons/master

Change filename in tox to updated name