Progressbar

This branches from reorg-utils. The appropriate diff is https://github.com/rmcgibbo/mixtape/compare/reorg-utils...progressbar?expand=1.

It uses https://code.google.com/p/python-progressbar/, which is LGPL, and just 3 files. Instead of introducing it as another dependencies, I just grafter it into the source tree, from https://code.google.com/p/python-progressbar/downloads/detail?name=progressbar-2.3.tar.gz