Fix regularization bug
Fix regularization bug

This fixes a bug in which weight regularization was not added to the
loss tensor, and thus it was not being used.  This corrects that, and
sets up the appropriate machinery to only add in regularization for
unfrozen layers.

Additionally, this cleans up the experiment folder name handling.

dusenberrymw/deep-histopath,dusenberrymw/deep-histopath