title: Flow package not installed in conda env creation
body: <p>I have no issue creating an conda environment with the given
  environment.yml file, but the flow package its self is not installed within the environment. I receive the following error when attempting to import flow within my env:</p>
  
  <p><code>ModuleNotFoundError: No module named 'flow'</code></p>
  
  <p>This is true on both macOS Mojave and Ubuntu 18.04.
  The work around is to install dependencies using pip.
  <code>pip install -e .</code></p>