Serve static files from within dcs-web

This makes it possible to run your own instance which looks exactly like
the one in production, but on your local machine without an nginx in
front :).
add the PostgreSQL schema to git
add howto/hacking.md, describing how to set up a tiny DCS instance

Note that this guide is not well tested yet, so please contribute
feedback (or pull requests!) to improve it :).
add testdata directory to git with files for a tiny hacking instance

These files are essentially a small Debian mirror with just the i3
package.
Merge branch 'master' into generalise