(maint) Stop stripping .cow suffix from cows

We used to strip the .cow suffix off in the pe_ship task, which meant
that the following regex that used the .cow suffix would never match.
This commit removes the .map and also tightens the following regex
slightly.
Merge pull request #357 from haus/maint/master/fixup_cow_regex

Remove non-existent .cow suffix from the deb regex