Use Ansible instead of a shell script to deploy the site from Jenkins.

Use it to manage the deployment and configuration of the node.js backend (#375) as well. Retargeted from #378.
Haha, yes. It would take one more manual step out of the README. And this is all Yet Another Pull Request that I probably won't do for a while so I can start tackling some other Ruby stuff I've been letting slide :wink: