Support the wacky prefixes in CDS unit format
Adds a test that was able to reproduce the problem in #1256 (on Python 3.2 at least, on other versions it doesn't appear to be an issue for some reason, probably due to subtle differences in the import implementation between those versions). Fixes the issue more or less in the way I suggested in the issue.
Merge pull request #1256 from embray/issue-1256

AttributeError in _find_pkg_data_path with Python 3.2
Added a changelog entry
Merge pull request #1426 from mdboom/unit/cds-prefixes-faux

Support the wacky prefixes in CDS unit format
Added changelog entry for #1426