Add model description to view item

The description is only shown if not empty

JIRA INFRA-280

app/templates/inventory/view_item.html

@@ -30,6 +30,10 @@
     <dd class="col-sm-9">{{ item.manufacturer }}</dd>
     <dt class="col-sm-3">Model</dt>
     <dd class="col-sm-9">{{ item.model }}</dd>
+    {% if item.model.description %}
+    <dt class="col-sm-3">Model description</dt>
+    <dd class="col-sm-9">{{ item.model.description }}</dd>
+    {% endif %}
     <dt class="col-sm-3">Location</dt>
     <dd class="col-sm-9">{{ item.location }}</dd>
     <dt class="col-sm-3">Status</dt>