Basic but functional list creation.
Rename `all_having_parents` to `all_children`.
Add spec for Sector model.
Various non-JS interface tweaks.
Integrate admin template.
JavaScript XHR interface for ordering within lists.

Also handles moving things between lists.
Allow ordering of lists within a sector.
Confirm before deleting lists.
Only send XHR updates if necessary for content rows.
Fix bug creating new lists.
Use titles instead of API URLs in JS interface.
Provide move indications on hover.
Allow editing of list names.
Tidy up list edit/delete controls.
Add an index for `sector_id` on `lists`.
Tighten up styling.
Merge pull request #1 from alphagov/add-curated-lists

Add curated lists