add `MeasurementUnitAbbreviation`
Merge pull request #189 from bitzesty/measurement-unit-abbreviation

Add in MeasurementUnitAbbreviations table
Remove router-client and rake task.

These are redundant (and were for talking to the old router).
Merge pull request #190 from alphagov/remove_router_client

Remove router-client and rake task.
Bump gds-sso to 9.3.0

This is to fix an issue with transfer ot bearer tokens. See
https://github.com/alphagov/signonotron2/pull/245 for details.

Bumped plek to get development mode default values.