added license

Author: cbernet

LICENSE

@@ -0,0 +1,17 @@
+heppy, a lightweight python high-energy physics event processing framework based on ROOT
+
+Copyright (C) 2014 Colin Bernet
+
+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/>.
+
+contact: Colin Bernet at CERN.ch