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 
They look like they have display issues. Not much point in providing an SVG screenshot if it isn't a good representation. If you are trying to represent the visuals of the theme then it should be a screen shot. Just be sure to optimize the image files to keep the total gzipped page size below 500kb (and as close to 200kb as possible).