Update unfold_protein to use the new pyafm.storage._load_afm.

Update unfold_protein to use the new pyafm.storage._load_afm.

This is a messy commit to get my Git repo in sync with the version I'm
currently using in the lab, but most of the changes have to do with
the nested-config overhaul starting with pypiezo's:

  commit de497a3734372f5fa7c92d6ff7bdb6b2e327c345
  Author: W. Trevor King <wking@drexel.edu>
  Date:   Thu Mar 15 10:13:20 2012 -0400

    Optional config-based-setup for PiezoAxis, OutputChannel, and InputChannel.

    See the module docstring for details on why this is useful.