Remove unused import and fix python3 compatibility, as per Ozielsaacs comments.

cps/kobo_auth.py

@@ -1,3 +1,23 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
+#  This file is part of the Calibre-Web (https://github.com/janeczku/calibre-web)
+#    Copyright (C) 2018-2019 shavitmichael, OzzieIsaacs
+#
+#  This program is free software: you can redistribute it and/or modify
+#  it under the terms of the GNU General Public License as published by
+#  the Free Software Foundation, either version 3 of the License, or
+#  (at your option) any later version.
+#
+#  This program is distributed in the hope that it will be useful,
+#  but WITHOUT ANY WARRANTY; without even the implied warranty of
+#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+#  GNU General Public License for more details.
+#
+#  You should have received a copy of the GNU General Public License
+#  along with this program. If not, see <http://www.gnu.org/licenses/>.
+
+
 """This module is used to control authentication/authorization of Kobo sync requests.
 This module also includes research notes into the auth protocol used by Kobo devices.