TRIBS-147 FTT Tax Add data models and import scripts

TRIBS-147 FTT Tax Fix data models and import scripts

TRIBS-150 FTT Tax Add docs

TRIBS-150 FTT Tax Fix rake task for docs

TRIBS-150 FTT Tax Add tests for doc processing

TRIBS-150 FTT Tax fix formatting
Merge pull request #69 from ministryofjustice/ftt-import

TRIBS-147 FTT Tax Add data models and import scripts