Format SRAT Response For App
Format SRAT Response For App

* Structure the SRAT response so that its keys and
  general schema generally match our other GWLF-E results.

* Sum the results for each HUC-12 into the attenuated results
  for the entire shape and include them in the payload

Results now look like this:

```json
{
    'Loads': [ {'Source': 'Hay/Pasture',  ...}, ... ],
    'AreaTotal': 1234.123,
    'inputmod_hash: "1j2j41k2232135212355678...",
    'HUC-12s': {
        '123456789120': { // huc12 id
            'Loads': [ {'Source': 'Hay/Pasture', ...} ...],
            'AreaTotal': 400.10,
            'Catchments': {
                '101010': { // comid
                    'TotalLoadingRates': { 'TotalN': ... },
                    'LoadingRateConcentrations': { 'TotalN': ... }
                }, ...
            }
        }, ...
    }
}

A few things to note:
 * These will look similar to the 'Water Quality' result of unattenuated
   GWLF-E runs. There is no `Hydrology` view for subbasin

 * I have omitted some keys at each level while we determine the final
   form of the tables. Notably missing is the `SummaryLoad` at the
   aggregate and HUC-12 level.

WikiWatershed/model-my-watershed,WikiWatershed/model-my-watershed,WikiWatershed/model-my-watershed,WikiWatershed/model-my-watershed,WikiWatershed/model-my-watershed