udpated with bettter logic for adding to installer/uninstaller/code updater

git-svn-id: svn+ssh://civmxsrv2.duhs.duke.edu/Users/civmsvn/svn/repos/workstation_code/trunk@2136 d41079a3-eaa1-4f09-8506-b324c47726bb
added a MAIN_DIR global for sub scripts to refer to. This was specifically added to handle things in svn_externals processing

git-svn-id: svn+ssh://civmxsrv2.duhs.duke.edu/Users/civmsvn/svn/repos/workstation_code/trunk@2137 d41079a3-eaa1-4f09-8506-b324c47726bb