Added current AllegroServe and replaced Python test server with it.

Added a temporary snapshot of current AllegroServe into cl-site repository (we'll have to carry it here until it manages to get into Quicklisp -- I'm working on that). Changed default make serve command to publish & serve from CL/aserve instead of Python. By default, loading build.lisp will now start serving the cl-site on localhost:8008.

Keeping the python server around for now for compatibility testing, benchmarking, etc.