requirements.txt doesn't match the requirements of the default code

[patrickmineault]

It's a little confusing that the requirements in version.py differ from those in requirements.txt. You have to both install requirements.txt and -e for the code to work, and then you get a scary error about missing duecredit, so you also have to pip install duecredit. I can submit a PR, what would be the preferred route? Adding a -e . to requirements.txt, or changing the requirements in version.py?