use wheezy version of stanford.list for trusty servers

templates/os/sources/stanford.list.erb

@@ -3,7 +3,7 @@
    # Map Ubuntu distributions to Debian distributions since we don't
    # currently have any repositories targeted for Ubuntu releases.
    if @operatingsystem == 'Ubuntu'
-     if @lsbdistcodename == 'raring'
+     if (@lsbdistcodename =~ /raring|trusty/)
        dist = 'wheezy'
      else
        dist = 'squeeze'