Remove PersonOne class.
Remove PersonOne and PersonOther models

Use only Person model
Add allow_blanks param to Person.new to optionally disable validation on
person's income.
Fix Welsh mode
Change affordability page model into multiple classes
Move page models into Affordability module
Explode affordability page class into multiple classes

```ruby
UI::Pages::Affordability::StepOne – Three
```
WIP more readable cucumber features
WIP Change cucumber tests

Remove all old tests
Add tests with easier to read descriptions
Improve test coverage
Add financial exampls to yml file for use in cukes
Add new cucumber test suite
Fix merge conflict
Merge branch 'master' into spike/only_one_person_model
Merge pull request #202 from moneyadviceservice/spike/only_one_person_model

Remove PersonOne and PersonOther models