Pypi package installs conflicting dependencies

[undu]

Steps to reproduce in arch (pip 9.0.1):

• Set up a python2 virtual environment with --no-site-packages
• pip install cwlref-runner
• pipconflictchecker

Result:

--------------------------------------------------
 Conflicts Detected
--------------------------------------------------
 - html5lib(0.999999999) schema-salad(<=0.9999999,>=0.90)

Workaround:
Install html5lib before cwlref-runner with pip install -I html5lib==0.9999999, first make sure to uninstall both cwlref-runner and html5lib.

It may be related to the recent ab9e86e

[tetron]

Thanks, I have been engaged in an ongoing battle with dependencies and this made me realize that requirements.txt may be out of sync with setup.py, which might be the problem. I'm not familiar with pipconflictchecker but that looks like something we should add to the test pipeline.

[mr-c]

I believe I have fixed the root problem in schema-salad -- I've also enabled pipconflictchecker in schema-salad and cwltool and made new releases.

#255
#257

This issue is presumable related to #255
@undu and @prismofeverything can verify?

[undu]

LGTM

[mr-c]

Thanks!