Ensure setuptools is present in the environment before invoking setup.py from easy_install. Fixes #319.

Make sure to monkey-patch the easy_install module in the setup context. Fixes the other former test failure. Ref #315.

Catch, save, and restore any exceptions across the save_modules context. This corrects the latter of the two test failures. Ref #315.

Restores purging of distutils/setuptools during sandbox operations. Ref #315.