Lots of refactoring

Tidy up lots of ugly things:

* Configuration format has been vastly simplified (<routes></routes>)
* Parsing the configuration with XPath has massively reduced complexity
* Configuration storage format sucks 50% less!
* GovernorActivity correctly displays the port number from config.xml
* HTTP requests are starting to get served based on configuration
* Documentation is starting to happen :o
Add awareness of MIME types to assets