Add has_discrepancies
Standardise encoding for hstore in Birmingham Cabinet

- Encode to JSON everywhere using encode_dict and decode_dict
- Remove DictSerialisable
Rename encode_dict and decode_dict to json_encode and json_decode
Remove redundant model config
Put employer_id on Claim

- This allows us to pull claims out of the database by employer
Remove _stringify function

- JSON encoding into HSTORE is fixed now
Merge branch 'master' into ip-dashboard

Conflicts:
	redundancy_payments_alpha/claim_service/discrepancies.py
	redundancy_payments_alpha/unit_tests/claim_service/test_find_discrepancies.py
Merge branch 'master' into ip-dashboard

Conflicts:
	redundancy_payments_alpha/birmingham_cabinet/api.py
Merge branch 'master' into ip-dashboard
Merge pull request #66 from InsolvencyService/ip-dashboard

Add employer_id column to Claim model and other refactorings