installer moved prereqs file to be named more appropriately, we are checking for required programs, and for a subset of them we are installing.

git-svn-id: svn+ssh://civmxsrv2.duhs.duke.edu/Users/civmsvn/svn/repos/workstation_code/trunk@2128 d41079a3-eaa1-4f09-8506-b324c47726bb