title: No route matches "/users/sign_out" devise rails 3
body: <p>I've installed devise on my app and applied the following in my <code>application.html.erb</code> file:</p>
  
  <pre><code>&lt;div id="user_nav"&gt;
      &lt;% if user_signed_in? %&gt;
          Signed in as &lt;%= current_user.email %&gt;. This cannot be cheese?
          &lt;%= link_to 'Sign out', destroy_user_session_path %&gt;
      &lt;% else %&gt;
          &lt;%= link_to 'Register', new_user_registration_path %&gt; or &lt;%= link_to 'Sign in', new_user_session_path %&gt;
      &lt;% end %&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>I ran <code>rake routes</code> and confirmed that all the routes are valid.</p>
  
  <p>Also, in my <code>routes.rb</code> file I have <code>devise_for :users</code> and <code>root :to =&gt; "home#index"</code>. </p>
  
  <p>I get the following routing error when clicking the "Sign out" link:</p>
  
  <pre><code>No route matches "/users/sign_out"
  </code></pre>
  
  <p>Any ideas what's causing the error?</p>