Add support for CSG-adjusted UCLA dataset

[cawarren]

The script currently doesn't run on actual UCLA datasets due to issue #6. To get it to run, we have to add an additional dataset which is UCLA + several new data points from CSG's research. Further, we should add this dataset for the benefit of its additional data points.

Adding support for the CSG dataset requires the following changes:

• In aggregate.py / aggregate():

  datasets = {'covidprisondata.com': load_data_dir('covidprisondata.com'),
              'UCLA Law Behind Bars': load_data_dir('ucla'),
              'UCLA Law Behind Bars - CSG Edit': load_data_dir('csg'),
              'Recidiviz': data.fetch_csv(constants.RECIDIVIZ_DATA_URL, as_dicts=True)}

Additionally, constants.py has to be updated to accommodate both mappings.

  'UCLA Law Behind Bars - CSG Edit': {#'Facility': '',  # facility type, e.g., "Prison"
                           'State': 'State',  # Federal facilities have value of "Federal" for this column
                           'Name': SOURCE_FACILITY_NAME_COLUMN,
                           'Staff Confirmed': 'Staff Tested Positive',
                           'Residents confirmed': 'Pop Tested Positive',
                           'Staff Deaths': 'Staff Deaths',
                           'Resident Deaths': 'Pop Deaths',
                           'Date': 'Date'},
  'UCLA Law Behind Bars': {#'Facility': '',  # facility type, e.g., "Prison"
                           'State': 'State',  # Federal facilities have value of "Federal" for this column
                           'Name': SOURCE_FACILITY_NAME_COLUMN,
                           'Staff Confirmed': 'Staff Tested Positive',
                           'Residents confirmed': 'Pop Tested Positive',
                           'Staff Deaths': 'Staff Deaths',
                           'Resident Deaths': 'Pop Deaths',
                           'Date': 'Date',
                           'Website': 'Source',
                           'Staff Tested': 'Staff Tested',
                           'Residents Tested': 'Pop Tested'},
                           #"Add'l Notes":'Notes'},