Fix minilib task to work when run from paver-minilib.zip.
Fix minilib task to work when run from paver-minilib.zip.

This makes minilib compatible with zipimport, and any other Python
import hooks as a side benefit.

Fixes issue #17

gregorynicholas/paver,phargogh/paver,cecedille1/paver,thedrow/paver,cecedille1/paver,gregorynicholas/paver,nikolas/paver