Make it possible to use builtin avatars

Images are from openclipart.org

calsocial/templates/profile-details.html

@@ -1,14 +1,17 @@
 {% extends 'base.html' %}
 
 {% block content %}
-<h1>
+<h2 class="ui header">
+    {% if profile.builtin_avatar %}
+    <img src="{{ url_for('static', filename='avatars/' + profile.builtin_avatar + '.svg') }}" alt="" class="ui circular image">
+    {% endif %}
     {% if profile.locked %}
     <i class="fa fa-lock" aria-hidden="true" title="{% trans %}locked profile{% endtrans %}"></i>
     <span class="sr-only">{% trans %}locked profile{% endtrans %}</span>
     {% endif %}
     {{ profile.display_name }}
     <small>@{{ profile.user.username}}</small>
-</h1>
+</h2>
     {% if profile.user != current_user %}
 <a href="{{ url_for('follow_user', username=profile.user.username) }}">{% trans %}Follow{% endtrans %}</a>
     {% endif %}