title: How to make nosetests use python3
body: <p>I try to use <code>nosetests</code><br>
      ❯ nosetests '/pathTo/test'</p>
  
  <p>but it uses <code>python 2.7</code> for my tests:</p>
  
  <pre><code>sys.version_info(major=2, minor=7, micro=5, releaselevel='final', serial=0)
  </code></pre>
  
  <p>So some of them fails, because they were written in <code>python 3.3</code>.</p>
  
  <p>I work it around and installed virtual environment: </p>
  
  <pre><code>pyvenv-3.3 py3env
  </code></pre>
  
  <p>Activated it:</p>
  
  <pre><code>source ~/py3env/bin/activate
  </code></pre>
  
  <p>Check python virsion in virtual environment:</p>
  
  <pre><code>❯ python --version                                                                                 ⏎
  Python 3.3.3
  (py3env)
  </code></pre>
  
  <p>Ok.
  But nosetest still uses <code>python2.7</code> even in virtual environment: </p>
  
  <pre><code>sys.version_info(major=2, minor=7, micro=5, releaselevel='final', serial=0)
  </code></pre>
  
  <p>So my tests fails. 
  <strong>How to make nose use python3?</strong></p>