Add an endpoint similar to the subbasin huc12s endpoint
to fetch the id, area, shape, and streams for a set of
catchment ids.

GET
/mmw/modeling/subbasins/catchments/?catchment_comids=%255B%25224780661%2522%252C%25224780663%2522%252C%25224780665%2522%252C%25224780751%2522%252C%25224782293%2522%252C%25224782295%2522%252C%25224782297%2522%252C%25224782307%2522%255D

-- where `catchment_comids` is a urlencoded json array

Response:
[
    {
        "id": 423312 // comid
        "shape": { "type": "MultiPolygon", ...}, // catchment geojson
        "stream": { "type": "MultiLineString", ...}, // stream geojson
        "area": 4.3111 // area in hectares
    }, ...
]

When entering the HUC-12-level view, fetch
the catchment details if they have not already
been fetched. This provides us the catchment area to
eventually calculate the rates, as well as the geometries.

Add template and view to display catchment loads for
an active HUC-12 in subbasin view.

The huc-12 totals table re-renders after the huc12 details
change. After every re-render the bootstrap table must be
reinitialized.

Fix a bug where if you switched to Analyze or Model views
while you were viewing a HUC-12 in subbasin mode, the shapes
would not get re-added to the map after coming back to the subbasin
view.

Use the helper function to clear the subbasin shapes
when exiting subbasin mode instead of clearing the collection.
The helper function removes the map listeners, which would otherwise
try to fire on removed layers.

The huc12 view should only be rendered if there's
an active huc12 to populate it with.