Copyright for python-py-zipkin source package in Bionic

Format: http://www.debian.org/doc/packaging-manuals/copyright-format/1.0/
Upstream-Name: py_zipkin
Upstream-Contact: Yelp, Inc. 
Source: https://github.com/Yelp/py_zipkin

Files: py_zipkin/thrift/zipkinCore.thrift
Copyright: 2012 Twitter Inc.
License: Apache-2.0

Files: *
Copyright: Yelp, Inc. 
License: Apache-2.0

Files: debian/*
Copyright: 2015 © Olivier Sallou 
License: Apache-2.0

License: Apache-2.0
 Apache-2.0 license file can be found at /usr/share/common-licenses/Apache-2.0.