Move to jinja

The current site has been ported to Jinja. I'll now port the Plugins and Changelog page too, so that they don't have to rely on Javascript.
host and port should configurable somewhere, e.g. in a settings.py.sample (which has to then be copied to settings.py by the server admin). Speaking of settings, you can also add some for the directories where the picard/picard-plugins repositories live on the server.