Dataframe of GridLAB-D has binary strings

[trevorhardy]

The data converter that reads the GridLAB-D HDF5 files is interpreting strings as binary values. For example, when I look at the data for the TE30 example, and ask for the names of the inverters, the values are binary strings:b'inv_F1_house_A11'. These should be converted to string datatypes on ingest.