Add background task to update half-loaded references

[cwhelchel]

Is your feature request related to a problem? Please describe.
In latest ver (0.0.10-devC), if you import reference hunts (hunter_parks.csv or others) the rows are left with no Location info. This is by design for imports but it renders the location numbers totally useless as that park data won't be included in the query to return 'number of parks hunted in a given location'.

Describe the solution you'd like
Those references need their data pulled from their respective API (pota, sota, etc). But this needs to be an idle task or otherwise in the background and not cause disruption to the user.

context
the old pota import would import the file and then pull the park info for every hunted park (thousands of parks) this was way to slow and very mean to do to the pota endpoints