[ADD] representatives section

...patterns/molecules/articles/main-article-preview.mustache

...de/source/_patterns/molecules/representative-box.mustache

...uide/source/_patterns/organisms/articles-section.mustache

...urce/_patterns/organisms/representatives-section.mustache

...guide/source/_patterns/organisms/twitter-section.mustache

main/styleguide/source/_patterns/templates/homepage.mustache

main/styleguide/source/css/atoms/container.pcss

main/styleguide/source/css/atoms/heading.pcss

...leguide/source/js/components/articles/ArticleCarousel.vue

main/styleguide/source/js/main.js