ModelWrapper Json changes

- Add (global/tropical) GAUL code to GeoJson
- Add disease extent class table to DB, to include weighting, referenced by two tables: admin_unit_disease_extent_class and admin_unit_review (the expert's response). DiseaseExtentClass changed from enum to entity with DAO.
- Change JsonModelRun extents list of gaul codes to map with weightings.
- Improve code coverage across GeoJson tests