title: Error when importing flask.ext.markdown
body: <p>I have the following code :</p>
  
  <pre><code>#!/usr/bin/env python2
  #coding: utf-8
  
  from flask import Flask, render_template
  from flask.ext.flatpages import FlatPages
  from flask.ext.markdown import Markdown
  </code></pre>
  
  <p>But when I try to run it, this error occurs : <code>ImportError: No module named flask.ext.markdown</code> whereas normally this module is existing. </p>
  
  <p>Is there somebody who can say how to fix that ?</p>