Server should run as a system service

[pchote]

Relying on a screen session (see INSTALL.md) is horrible. The resource center is now also running in a dedicated VM, so the virtualenvwrapper is unnecessary complexity.

https://github.com/warwick-one-metre/dashboard (dashboard.service, dashboard.ini) provides an example of how to run gunicorn through systemd, allowing it to automatically start on system boot, restart if it crashes, and generally be managed like any other service through systemctl.