Use package for writing versioninfo.

This currently fails for client projects as python_package
is the name of the project, while package is where versioninfo
is written to. This doesn't affect server openstack projects
because python_package == package.

This hasn't affected any client projects yet because most likely
none of them call version.canonical_version_string() in their
setup.py

Change-Id: Ia97e5fae378c47909f3dbc842dc83e408af68671
Merge "Use package for writing versioninfo."