Add data management page. Closes #61.

biscuit/core/templates/core/data_management.html

+{# -*- engine:django -*- #}
+{% extends "core/base.html" %}
+{% load bootstrap4 menu_generator %}
+
+{% block page_title %}BiscuIT administration{% endblock %}
+
+{% block content %}
+{% get_menu "DATA_MANAGEMENT_MENU" as data_menu %}
+<ul>
+ {% for item in data_menu %}
+  {% if not item.submenu %}
+   <li><a href="{{ item.url }}">{{ item.name }}</a></li>
+  {% endif %}
+  {% if item.submenu %}
+   <li><a href="{{ item.url }}">{{ item.name }}</a></li>
+    <ul>
+     {% for menu in item.submenu %}
+      <li><a href="{{ menu.url }}">{{ menu.name }}</a></li>
+     {% endfor %}
+    </ul>
+  {% endif %}
+ {% endfor %}
+</ul>
+{% endblock %}