Switch to a dual GPL/APL licensing model

At the request of HP, we switch to a dual GPL/APL model to make it
possible to use python-hpilo with OpenStack projects.

All people who contributed have indicated their approval on
#85

COPYING

@@ -2,14 +2,17 @@ python-hpilo - Manage iLO interfaces from python code
 Copyright (C) 2011-2015 Dennis Kaarsemaker <[email protected]>
 
 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.
+it under the terms of (at your option) either the Apache License,
+Version 2.0, or 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.
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 
-You should have received a copy of the GNU General Public License
-along with this program.  If not, see <http://www.gnu.org/licenses/>.
+For details and specific language governing permissions and
+limitations, see either
+
+ - http://www.gnu.org/licenses/ for the GNU GPL
+ - http://www.apache.org/licenses/LICENSE-2.0 for the Apache license

setup.py

@@ -15,6 +15,7 @@
         'Intended Audience :: Developers',
         'Intended Audience :: System Administrators',
         'License :: OSI Approved :: GNU General Public License (GPL)',
+        'License :: OSI Approved :: Apache Software License',
         'Programming Language :: Python',
         'Programming Language :: Python :: 3',
         'Topic :: System :: Hardware',