Automatically find/download setuptools and make it available on sys.path
`version` should be a valid setuptools version number that is available as an egg for download under the `download_base` URL (which should end with a '/'). `to_dir` is the directory where setuptools will be downloaded, if it is not already available. If `download_delay` is specified, it should be the number of seconds that will be paused before initiating a download, should one be required. If an older version of setuptools is installed, this routine will print a message to “sys.stderr“ and raise SystemExit in an attempt to abort the calling script.