patched $DISPLAY error for Systemd

modified indentation server_thread function

py-kms/pykms_Server.py

@@ -263,4 +263,7 @@ if __name__ == "__main__":
         if sys.stdout.isatty():
                 srv_main_without_gui()
         else:
+                try:
                         srv_main_with_gui()
+                except:
+                        srv_main_without_gui()