Make Jetty use the jarfile's path

Previously, the webserver was loading content from the current working
directory. This reworks some code so that we form an actual object so
that we can get access to the class loader, but I think it's actually a
positive move regardless.

Now, going to localhost:8080 should serve the demo.html file to you. You
can change the url by hand for now to get to our other html files.
Use camelCase everywhere in JettyServer

While I personally enjoy under_scores, it's not the convention in Java,
and "when in Rome, do as the Romans do".
Remove Servlet, because we aren't using it

It'll still be in the commit history, and it may be useful in the
JSON-serving backend component, but since we're only serving static
content, it doesn't make sense here.
Get rid of unused imports in JettyServer
Enable logging, and use log4j

log4j is Apache's logger. It gives us tons of stuff we'll never use, but
it's simple enough to install with Maven, so why not?