setup: make Xcode 5.1 check less specific

Was failing on "5.1\n".

--HG--
extra : rebase_source : ed958ad7394b336bdd226d036ae681a4819f1313
make: add a basic osx mpkg target

--HG--
extra : rebase_source : e2fd99ed0d1e3665241641bc77514fd424158f00
packaging: move output directory from build/ to packages/

setuptools owns build/ and dist/ and we want to have our own scheme