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 
I will return this line in the file, however, it could be an issue for this alert to be displayed in the dark blue page banner - it will break it apart. How else can we display the notice?