Removed empty conference type lists on conference list page

app/views/conferences/list.html.haml

@@ -18,6 +18,7 @@
   = row do
     = columns(medium: 12, id: :conferences, class: 'list-view') do
       - @conference_list.each do | type, list |
+        - if list.present?
           %h3=_"articles.conferences.headings.types.#{type.to_s}", :t
           %ul
             - list.each do | conference |