Fix "ImportError: No module named six"

The six module is not a dependency of setuptools==36.0.0 that is why
we need to explicitly install it. It is a temporary fix.

Fixes: ansible#569

container/docker/templates/conductor-dockerfile.j2

@@ -42,7 +42,9 @@ RUN python /get-pip.py && \
 
 # The COPY here will break cache if the version of conductor changed
 COPY /container-src /_ansible/container
+# Fix: 'pip install six' is a temporary fix for setuptools==36.0.0 bug
 RUN cd /_ansible && \
+ pip install six && \
  pip install -r container/conductor-build/conductor-requirements.txt && \
  PYTHONPATH=. LC_ALL="en_US.UTF-8" python container/conductor-build/setup.py develop -v && \
  ansible-galaxy install -p /etc/ansible/roles -r container/conductor-build/conductor-requirements.yml