RF: bdist_wininst, add bdist_mpkg as setuptools

bdist_wininst does not need to be setuptools, so remove it from the list
of commands requiring setuptools.

We use bdist_mpkg to make OSX installers, so add this as a setuptools
command.
BF: point setup at bin directory to find scripts

We were pointing at 'scripts', which we don't have...
Merge pull request #154 from matthew-brett/massage-setuptools-commands

RF: bdist_wininst, add bdist_mpkg as setuptools