Fixes #725. Moved the cython_version.py generation until after the normal build_ext command runs.  There was really no specific reason for it to go first.  Also check to ensure that the build/lib directory exists yet before doing anything with it.
Merge pull request #725 from iguananaut/issue-725

./setup.py develop doesn't work in a fresh checkout
#865: Provide a way to hide the download progress.