title: express 3 get session in all template
body: <p>I'm using express <code>v3.x</code></p>
  
  <p>before i was able to send a dynamic helper to <strong>all</strong> my template via</p>
  
  <pre><code>app.dynamicHelpers({
    session: function (req, res) {
      return req.session;
    }
  })
  </code></pre>
  
  <p>now in 3.x we got <code>res.locals</code>
  but when providing a function it doesn't inject <code>req</code> param</p>
  
  <p>ex :
  <code>res.locals.session = function (req, res) { return req.session; }</code></p>
  
  <p><code>req</code> is <code>undefined</code></p>
  
  <p>how can i handle that beside setting session in every <code>render</code> function ??</p>