sets debate's title as title page in debate/show

app/views/debates/show.html.erb

@@ -1,3 +1,4 @@
+<% provide :title do %><%= @debate.title %><% end %>
 <% cache [locale_and_user_status(@debate), @debate, @debate.author, Flag.flagged?(current_user, @debate), @debate_votes] do %>
   <section class="debate-show">
     <div id="<%= dom_id(@debate) %>" class="row">

spec/features/debates_spec.rb

@@ -44,6 +44,7 @@ feature 'Debates' do
     expect(page).to have_content debate.author.name
     expect(page).to have_content I18n.l(debate.created_at.to_date)
     expect(page).to have_selector(avatar(debate.author.name))
+    expect(page.html).to include "<title>#{debate.title}</title>"
 
     within('.social-share-button') do
       expect(page.all('a').count).to be(3) # Twitter, Facebook, Google+