title: set_language not working in django internationalization
body: <ol>
  <li><p>I included the following in the settings.py:</p>
  
  <pre><code>LANGUAGES = (
      ('en', 'English'),
      ('ru', 'Russian'),
  )
  
  LANGUAGE_CODE = 'en-us'
  
  USE_I18N = True
  </code></pre></li>
  <li><p>marked the strings to be translated</p>
  
  <pre><code>_('Enterprise')     # _ is lazy translate
  </code></pre></li>
  <li><p>included this in my URLCOnf:</p>
  
  <pre><code>url(r'^i18n/', include('django.conf.urls.i18n'))
  </code></pre></li>
  <li><p>created the locale folder and did this:</p>
  
  <pre><code>python manage.py makemessages -l ru
  </code></pre></li>
  <li><p>translated the strings and did this:</p>
  
  <pre><code>python manage.py compilemessages
  </code></pre></li>
  <li><p>wrote this form:</p>
  
  <pre><code>&lt;form action="/i18n/setlang/" method="post"&gt;
          {% csrf_token %}
          &lt;input name="next" type="hidden" value="/" /&gt;
          &lt;select name="language"&gt;
             {% for lang in LANGUAGES %}
             &lt;option value="{{ lang.0 }}"&gt;{{ lang.1 }}&lt;/option&gt;
             {% endfor %}
          &lt;/select&gt;
          &lt;input type="submit" value="Translate" /&gt;
   &lt;/form&gt;
  </code></pre></li>
  </ol>
  
  <p>I think I did all the steps to make it work but seems like I doing something wrong or missing something.</p>
  
  <p>When use the form and try to translate and print <code>request.LANGUAGE_CODE</code>, it is showing me expected value. But the strings remain in the same language as they were</p>
  
  <p>What is wrong here?</p>