add license information (#4)

credentials.py

@@ -1,2 +1,21 @@
+#!/usr/bin/env python3
+#
+# Telegram bot to play UNO in group chats
+# Copyright (c) 2016 Jannes Höke <uno@jhoeke.de>
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero 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 Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+
+
 TOKEN = 'TOKEN'
 BOTAN_TOKEN = ''  # Optional: Add a botan.io token if you want bot statistics