feat(network): Add style to network

Style nodes and edges of network
Fix layout of network not running

See #14

breccia_mapper/templates/base.html

@@ -73,6 +73,10 @@
                             <a href="{% url 'activities:activity.list' %}" class="nav-link">Activities</a>
                         </li>
 
+                        <li class="nav-item">
+                            <a href="{% url 'people:network' %}" class="nav-link">Network</a>
+                        </li>
+
                         {% if request.user.is_superuser %}
                             <li class="nav-item">
                                 <a href="{% url 'admin:index' %}" class="nav-link">Admin</a>