Resolve "Register absences and excuses centrally"

Closes #2 (closed)

biscuit/apps/alsijil/templates/alsijil/manage_absence.html

+{# -*- engine:django -*- #}
+{% extends "core/base.html" %}
+{% load bootstrap4 i18n static %}
+
+{% block bootstrap4_extra_head %}
+  {{ block.super }}
+  {{ manage_absence_form.media.css }}
+{% endblock %}
+
+{% block bootstrap4_extra_script %}
+  {{ block.super }}
+  {{ manage_absence_form.media.js }}
+{% endblock %}
+
+{% block bootstrap4_title %}{% blocktrans%}Manage absence{% endblocktrans %} - {{ block.super }}{% endblock %}
+
+{% block page_title %}Manage absences{% endblock %}
+
+{% block content %}
+
+  <form method="post">
+    {% csrf_token %}
+    {% bootstrap_form manage_absence_form %}
+    <button type="submit" class="btn btn-dark">
+      {% blocktrans %}Save{% endblocktrans %}
+    </button>
+  </form>
+
+{% endblock %}