This is the set up updates to finish moving urbansim to the new simulation framework

I'm certainly open to other ways of doing this, but this is my version of a ".loc" update on a wrapped dataframe.  I think we discussed this and this was the best way to do this (https://github.com/synthicity/urbansim/issues/53).  Also, this is re: the comment two below - this is always on a local column of the dataframe and not an added column.  Basically any time I run a prediction I'm going to update a column and I need to know the best way to do so - e.g.https://github.com/synthicity/bayarea_urbansim/blob/new-dataset-style/utils.py#L67.