This allows us to remove the ImportError hack from __init__.py.
It also simplifies how the package is versioned - deriving it solely
from the repository tag.
Both version_info and __version__ have been removed with this change.
Given how these are a unofficial-standard at best, I've found it safer to
always use pkg_resources to determine the version when I need to.
Distributing a raw python module into a namespace package seems to be
somewhat unreliable though I haven't proven it yet... In any case,
installing a package inside of a namespace package behaves itself.