fixed cert generation

vpngen.py

 
         call([".%sclean-all" % os.sep])
         call([pkitool, "--initca", "-batch"])
-        call([pkitool, "server", "-batch"])
+        call([pkitool, "--server", "server", "-batch"])
         call([".%sbuild-dh" % os.sep])
         call(["openssl", "ca", "-gencrl",
               "-keyfile", "keys%sca.key" % os.sep,