Add download_url

Adding the download url for releases, the version should match the
release

Author: Robert Monegro

setup.cfg

@@ -1,2 +1,2 @@
 [metadata]
-description-file = README.md
+description-file = README.md

setup.py

@@ -35,6 +35,7 @@
         ],
     install_requires=INSTALL_REQUIRES,
     url=URL,
+    download_url='https://github.com/redhat-aqe/python-kafka-logger/archive/{0}.tar.gz'.format(VERSION),
     description=SHORT_DESCRIPTION,
     long_description=DESCRIPTION,
     license=LICENSE,