Fix HTML title not displayed in map page

umap/templates/leaflet_storage/map_detail.html

 {% extends "base.html" %}
 {% load leaflet_storage_tags compress %}
-{% block title %}{{ map.name }}{% endblock %}
+{% block head_title %}{{ map.name }} - uMap{% endblock %}
 {% block body_class %}map_detail{% endblock %}
 
 {% block extra_head %}