Start to support verbosity levels

A crude first step towards supporting verbosity levels in output, per
#7.
Display a progress meter

Optionally show a graph indicating progress downloading the raw
committee data. This is towards #7, as a default verbosity level that's
less chatty than what we were doing. Note that it it doesn't work very
well -- it graphs a greater percentage than it should, although the
number is accurate.
Allow abbreviated flags to be used at the command line