Docker build fails because of Python dependency

[sebastianpoeplau]

Building a container with the supplied Dockerfile now fails because some Python dependency dropped support for Python 2 (and the versions are not pinned). As a workaround, I removed the dependency pytest-xdist from setup.py; then the container builds fine but obviously may not be capable of running the tests.

[insuyun]

Thanks. I should support python3 as noted in #60.

[bjchan9an]

We also failed to build the docker due to the installation of pytest-xdist. We modify the setup.sh to install pip with get-pip.py instead of apt-get(#77). This makes us install a new version of pip and successfully build the docker.

[insuyun]

#79 resolve this issues.