Importing a single boundary

A boundary for a single area can be imported using a command like:

manage.py boundaryline_import_boundaries --source "bdline_gb-2018-05" --code "gss:X01000001" -u "http://parlvid.mysociety.org/os/bdline_gb-2018-05.zip"

This is mainly useful for one-off organisation-level boundary changes, or when creating new organisation records.