Show chair for session on main overview page

Plus keep it a link so opt out is not impossible.

pinaxcon/templates/symposion/schedule/_grid.html

@@ -44,6 +44,8 @@
                         <em>Session chair:
                         {% if not session.chair %}
                           <a href="{% url "schedule_session_detail" session.id %}">Volunteer! 🙋</a>
+                        {% else %}
+                          <a href="{% url "schedule_session_detail" session.id %}">{{ session.chair.user.attendee.attendeeprofilebase.attendeeprofile.name }}</a>
                         {% endif %}</em>
                       {% endfor %}
                     </div>