fix setup.py URL

Author: xeroc

setup.py

@@ -19,7 +19,7 @@
     version=VERSION,
     description='Python library for bitshares',
     long_description=open('README.md').read(),
-    download_url='{}/tarball/{}'.format(VERSION, URL),
+    download_url='{}/tarball/{}'.format(URL, VERSION),
     author='Fabian Schuh',
     author_email='[email protected]',
     maintainer='Fabian Schuh',