Lack of OS X testing

[mr-c]

See https://groups.google.com/d/msg/common-workflow-language/AVxQ_-oFzgM/SK10kiTjCQAJ
& https://docs.travis-ci.com/user/osx-ci-environment/

[tfmorris]

I'd be willing to help with this, but I can't find even basic developer documentation (which I'm about to whine about in a new issue).

[mr-c]

This is solved, thanks to @stain et al!

http://ci.commonwl.org/view/All/job/cwltool-conformance-osx

• add OS X testing to the pull request builder