Add license grant

debian/copyright

@@ -6,4 +6,17 @@ Source: https://github.com/CygnusNetworks/pypureomapi
 Files: *
 Copyright: 2010-2015, Cygnus Networks GmbH <[email protected]>
 License: Apache-2.0
- See /usr/share/common-licenses/Apache-2.0
+ Licensed under the Apache License, Version 2.0 (the "License");
+ you may not use this file except in compliance with the License.
+ You may obtain a copy of the License at
+
+     http://www.apache.org/licenses/LICENSE-2.0
+
+ Unless required by applicable law or agreed to in writing, software
+ distributed under the License is distributed on an "AS IS" BASIS,
+ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ See the License for the specific language governing permissions and
+ limitations under the License.
+
+ On Debian systems, the complete text of the Apache License Version 2.0
+ can be found in `/usr/share/common-licenses/Apache-2.0'.