Disable old child maintenance scheme

On November 25 2013 the old 2003 Child Maintenance scheme becomes obsolete. So as to allow sufficient time for this change to be previewed, the scheme has been disabled rather than removed from the application. A technical debt story (https://www.pivotaltracker.com/s/projects/537731/stories/61214346) has been added to remove the now obsolete tests, logic and configuration data.

This pull request also includes some copy changes to the start and results page, and a change to the floor value for basic and reduced rate payments (from £5 to £7 to match new flat rate - see story https://www.pivotaltracker.com/s/projects/537731/stories/60237904).