Fix tabs on sign in page

app/views/devise/shared/_tab_single.html.haml

-%ul.nav-links.new-session-tabs.single-tab
+%ul.nav-links.new-session-tabs.single-tab.nav-tabs.nav
   %li.active
     %a= tab_title

app/views/devise/shared/_tabs_ldap.html.haml

-%ul.nav-links.new-session-tabs{ class: ('custom-provider-tabs' if form_based_providers.any?) }
+%ul.nav-links.new-session-tabs.nav-tabs.nav{ class: ('custom-provider-tabs' if form_based_providers.any?) }
   - if crowd_enabled?
     %li.active
       = link_to "Crowd", "#crowd", 'data-toggle' => 'tab'

app/views/devise/shared/_tabs_normal.html.haml

-%ul.nav-links.new-session-tabs{ role: 'tablist' }
+%ul.nav-links.new-session-tabs.nav-tabs.nav{ role: 'tablist' }
   %li.active{ role: 'presentation' }
     %a{ href: '#login-pane', data: { toggle: 'tab' }, role: 'tab' } Sign in
   - if allow_signup?