Added site-conf-example for creating designer from scratch

Added site-conf-example modification, to enable creating server from scratch (meaning server directory is empty)
- Added a site-conf-example directory, the script will use this if the $HOME/server/site-conf-example does not exist.
- Commented server.xml and context.xml since these files are not usually configured on the base tooltwist setup, they need to be added manually if the site requires too.