Add sitecheckin client and server, which will tell Utah (Mother Ship)
about Emulab sites. Nothing private, just the equivalent of calling testbed-version so that we know what sites exist and what software they are running. This is opt-out; sites that do not want to tell Utah about themselves can set NOSITECHECKIN in their defs file. In Utah, there is a new option in the Administration drop down menu to print out the list from the DB.