converting virtualenvwrapper repository to git

If you have forked virtualenvwrapper, you’ll want to update your fork to
use the new git repository at
https://bitbucket.org/dhellmann/virtualenvwrapper, still hosted by our
friends at bitbucket.org. The issue tracker contents have been migrated
along with the source code.

The old Mercurial repository is still available at
https://bitbucket.org/dhellmann/virtualenvwrapper-hg until I’m entirely
certain that the new repository is working correctly.