Add export capability for class summary view

templates/class.html

@@ -10,6 +10,9 @@
 
 {% block content %}
 <h2>{{ klass.name }}</h2>
+<div style="float:right;">
+    <a href="{% url 'class' object.pk %}?format=xls"><img src="{{ STATIC_URL}}img/xls.png" title="Exportation Excel" width="24"></a>
+</div>
 <h3>Récapitulatif des stages</h3>
 <table>
 {% for student in students %}