Fix problems with the transition to the new nested-Config h5config package.

Fix problems with the transition to the new nested-Config h5config package.

Also restore BumpConfig's `initial-position` setting, since it's
critical to running a bump.  I removed it when I mistakenly thought it
was storeing the output voltage used as the initial position
(something that you'd measure during a bump).  I guess I should have
read the help string before I deleted it ;).

There are also a number of numpy array -> float conversions when
loading HDF5.  This avoids excessive numpy-fication with h5py v2.0.