Full library url

1. LibraryServlet now adds its own url to sbt config, instead of server/library

2. WidgetWrapper tidied up, ActivityStream specific code moved to ActivityStreamWrapper, allows subclasses to specify a substitution mapping for their templates.

3. Added a splitQuery method to util.js which takes a query string and returns an object.

3. Added a url.js class using a regular expression I wrote, we can't use document.createElement in case we end up needing it to work server-side.