add alt attributes

shared/templates/styleguide2/404.html

shared/templates/styleguide2/feed_item_description.html

...lates/styleguide2/includes/atoms/articles/side_image.html

...d/templates/styleguide2/includes/atoms/figure/figure.html

...yleguide2/includes/atoms/youtube_video/youtube_video.html

...includes/molecules/articles/article_timeline_preview.html

...ncludes/molecules/candidates/candidate_secondary_box.html

...lates/styleguide2/includes/molecules/gallery/gallery.html

...eguide2/includes/molecules/popouts/hoax_popout_point.html

.../styleguide2/includes/molecules/popouts/popout_point.html

...plates/styleguide2/includes/organisms/faq/faq_answer.html

...includes/organisms/header/elections/candidate_header.html

...yleguide2/includes/organisms/layout/elections/navbar.html

...mplates/styleguide2/includes/organisms/layout/navbar.html