Upgrade setuptools

Fixes #14. This upgrades `setuptools` from the default version from apt before upgrading `pip` and `virtualenv`. For a new server this will install `setuptools` and `pip` from apt then upgrade `setuptools` using the current `pip` version. Then `pip` will upgrade itself. The one obvious place this will fail it the apt version of `pip` becomes so outdated that the most recent `setuptools` is no longer compatible.

**Note**: This does not fix servers which are already in a bad state with `setuptools < 0.8` and `pip >= 1.5`. Those servers need have `setuptools` upgraded manually.