Revert "the newest version of setuptools_git seems to work, so readding the dependency for it to setup_requires"

This reverts commit 21025e88182a4a552137ad21c3f46d2f006ca5b1.

Sorry, we don't want to use setup_requires here.  I should have closed this issue before asking Carlos to look at it.  Someone who simply uses this package should not need setuptools_git.

Please install setuptools_git by hand when you need to generate an sdist.
Merge branch 'master' of github.com:Pylons/deform