Prevent wrapping of mortgage calculator tabs

CSS for "small screen" mode kicks in at 570px instead of the standard
480px as the design for the mortgage calculator is non-standard
Styling borrowing range
Styling header for offer amount
Stripping unnecessary classes
Adding accents to numbers
affordability GA when user completes
Fire GA when user refines borrowing slider

Also fixes sliders firing GA events on initialise
Comment GA tests as break CI