Add st.sh script to build systemvm's for testing. This file builds a
file called sysvmoverlay.tar from
cloudstack/systemvm/patches/debian/config/* and
cloudstack/systemvm/patches/debian/vpn/* then starts a python web server
(python -m SimpleHTTPServer 8089 &) to allow the newly build sysvm to
get the changes to the scripts then kicks off the ./build.sh script to
build a sysvm from scratch.