json2db additional options

[ajparsons]

Option to just update one policy/descriptions in json2db

This is currently quite a slow update - but if needing to do a quick fix it’d be good to have the option to do just one.
Also a flag just for descriptions - you can just stop it quickly but that would be better

JSON2db does not remove old party comparisons from the database

In practice it is rarely an issue, but means you can’t create a Policies object using all policy_ids in the party comparison table (because some aren’t real).