Start work on V2 of childcare
Update structure following document changes

Start work on the mathematics and calculating costings.
Add in content for childcare v2
More implementation and testing for childcare calcs
Fix some weekly price calculations
Add phrases for outcomes
Split call helpline outcome into 2
Split call_helpline into 2 separate outcomes

Fix some mathematical bugs.
Add some phrase list tests
Remove now untrue comment
Output the cost difference formatted as Money
Merge pull request #254 from alphagov/childcare_v2

Childcare Tax Credits V2