Add an admin <title> consistent with non-admin pages

coin/templates/admin/base_site.html

@@ -9,7 +9,7 @@
     {% include 'autocomplete_light/static.html' %}
 {% endblock %}
 
-{% block title %}COIN ☺ Admin{% endblock %}
+{% block title %}Admin - COIN - {{ branding.shortname|capfirst }} SI{% endblock %}
 
 {% block branding %}
 {% hijack_notification %}