refactor form step 1
calculate applicants total lifestyle spend
calculate the estimated remaining per month minus key costs
refactor affordability feature spec to include new calculations
fix weird issue with null values from inputs
uncomment risk chart
Merge pull request #132 from moneyadviceservice/affordability_calculations

Affordability calculations
non-js affordability now works on multipage
fix tests due to extra page added
fix merge issue
correct cucumber specs
make feature specs run with and without javascript
fix js copy for borrowing range