Add new Getting Started page

Modified content in start-en.hbs to match the new theme, 
Added page specific css in content/_base,scss
Modified colours in main/_base.scss and footer/_base.scss
Modified link colours in _variables.scss 
@pjackson28 I'm not sure if I understand how I would put an ordered or unordered list for the steps when they're in details and summary which are in a "row". Aso, the step number requires a circle that is built with CSS. Either way, they're not really considered a list, just numbered items that the user doesn't have to follow from step 1 to 3 but can be used as guidance.