add tooltips with failed test links for failed images
    
    Oh man I love this so much! Huge thanks to Robery Mayr for help
    with the HTML/CSS here. You can now hover over the link for any
    image with test fails to show a tooltip with links to each of
    the failed tests in openQA, or the Autocloud test output page.
    Super cool. Woohoo. All in pure HTML/CSS, no stinky JS here.