[Distutils] ensurepip in Python 2.7

Hey all, The next 2.7 release is coming up in a few weeks, and work is still needed on getting the SSL infrastructure updated. That release will likely also be the first one with Steve Dower at the helm for the creation of the Windows installers. Accordingly, I think it makes sense to leave proposing backporting ensurepip until 2.7.8 in November at the earliest. (Fortunately, there's no pyvenv in 2.7, so unbundling for the Linux distros is much simpler) Cheers, Nick.