Moved the impact number to the right.
Add line to the bottom of single line graphs.

Remove the fill colour.
Fix styling on single-stat view.

Create a new summary element that holds the data instead of just appending to the end of the string.

Styling

Update tests.
Bring the single-stat in line with the new designs.
Added callout (tooltips) to the single line graphs.
Added isOneHundredPercent to the base graph class to stop tooltip erroring if it isn't added.
Merge pull request #693 from alphagov/feature/single-line-graphs

single line graphs updates...