app/views/authors/_author_nav_links.html.haml
.col-md-12
%ul.nav.nav-tabs
%li{ class: is_active(activated_page, 'show') }
= link_to 'Author', language_author_path(author.language, author)
%li{ class: is_active(activated_page, 'edit') }
= link_to 'Edit', edit_language_author_path(author.language, author)
%li{ class: is_active(activated_page, 'hitory') }
= link_to 'History', '#'