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 
How do the SVG images have display issues? Are you talking about the appearance of them? They are meant to look like they are graphic images of the themes which don't necessary need to have every single detail. This was discussed as a better solution to have in replacement of real screenshots of the themes for better loading time.