text: Title: CONTRIBUTING.md references wrong requirements file
  Body: CONTRIBUTING.md says to run `pip install -r requirements-dev.txt` but I believe it should be `pip install -r requirements-test.txt`.
  
  Also, is it worth mentioning that `pip install -r requirements.txt` or `pip install -r requirements-dev.txt` has to be run before `pip install -r requirements-test.txt`, or making requirements-test.txt reference requirements.txt so it's mildly more straight forward to install and test?