<li>
    <i class="milestone-default glyphicon {% if object.author_institution %}glyphicon-home{% elif object.author_user %}glyphicon-user{% else %}glyphicon-envelope{% endif %}"></i>
    {% include 'letter/_object.html' with object=object %}
  </li>

<li>
    <i class="milestone-default fa {% if object.author_institution %}fa-home{% elif object.author_user %}fa-user{% else %}fa-envelope{% endif %}"></i>
    {% include 'letter/_object.html' with object=object %}
  </li>

Fix fontawesome in milestone list
Fix fontawesome in milestone list
