Reinstate Ansible interpreter, deps for edX next_residential (#1147)
Reinstate Ansible interpreter, deps for edX next_residential (#1147)

In the next_residential pillar for the edX application, reinstate the
ansible_python_interpreter variable and the `virtualenv' Python
dependency. We want the Python interpreter to be 3.5 again and we want
virtualenv installed from pip.
mitodl/salt-ops,mitodl/salt-ops