added GPL3 license

hello_world.py

@@ -0,0 +1,28 @@
+# -*- coding: utf-8 -*-
+"""
+    hello_world.py tests the connection between github and zenodo
+    Copyright (C) 2018  B.F. de Boer
+
+    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 <https://www.gnu.org/licenses/>.
+
+"""
+
+def print_gpl3():
+    print('hello_world.py\tCopyright (C) 2018\tB.F. de Boer\n'
+          'This program comes with ABSOLUTELY NO WARRANTY\n'
+          'This is free software, and you are welcome to redistribute it'
+          ' under certain conditions')
+
+if __name__ == '__main__':
+    print_gpl3()