Put db/schema.rb back under source control

“It's strongly recommended to check this file into your version control
system.”
Rename CourtsAreasOfLaw model to Remit
Add backported is_expected helper

So we can write "it { is_expected.to ... }"
Introduce Jurisdiction model

This connects remits to councils, i.e. keeps track of the councils for
which a court is responsible in each area of law.
Populate jurisdictions from court council links

The Jurisdiction model will replace the CourtCouncilLink model. The
first step is to move all the data over.

This migration intentionally discards any CourtCouncilLink data which
associates a court with a council for an area of law outside of its
existing remit, because any such data is incorrect and was entered by
mistake.
Remove old ChildrenCourtCouncilLink model

It hasn’t been used since 2690275e0f36a80ab5deeb41d68d33aa5be96b20.
Expand hard tabs
Introduce add_councils_to_court spec helper

This decouples the examples from the detail of how courts and councils
are connected, which will make the implementation much easier to change.
Make Council.unassigned_for_area_of_law tests more comprehensive

This should provide more confidence that the scope is actually working
as advertised.
Clarify unassigned_for_area_of_law query

Looking for a null council_id is weird, because we’re selecting a list
of councils.
Find courts through jurisdictions

This removes half of the work that CourtCouncilLink was doing.
Find councils through jurisdictions

This removes the rest of CourtCouncilLink’s work.
Remove the CourtCouncilLink model

It’s no longer being used by anything.
Use jurisdictions in import:local_authorities_for_area_of_law Rake task
Use jurisdictions in export scripts
Drop the court_council_links table
Update Shippable Ruby version to match .ruby-version
Merge pull request #221 from ministryofjustice/introduce-jurisdictions

Introduce jurisdictions