Merge pull request #77 from ministryofjustice/migration

Migration
APOLLO-3348 Removed applicant factory as this is not used anymore
APOLLO-3348 Removed powerOfAttorneyFactory
APOLLO-3348 deleted exchangeArray
APOLLO-3348 ripped out  exchangeArray
APOLLO-3348 Removed any remnants of exchangeArray
APOLLO-3348 Cleaned up tests a bit
APOLLO-3348 Cleaned up tests a bit
APOLLO-3348 Improved validator
Merge pull request #80 from ministryofjustice/APOLLO-3348

Apollo 3348
Merge branch 'master' of github.com:ministryofjustice/opg-core-public-domain-model into migration