Per resource Datapusher+ job configuration

[jqnatividad]

If a resource extra field called "dpplus_job_config" is defined and contains a valid DP+ job configuration JSON, DP+ will apply the configuration just for that job.

This will allow us to selectively do things like geocoding, PII screening, auto-spatial extent calculation, and adding summary stats on a per job basis.

Perhaps, a standard DP+ scheming widget can be created with the necessary controls, so CKAN installations can quickly add a DP+ job configurator to the resource schema.