recreate form to have an icon for the calendar

templates/download.html

@@ -16,8 +16,43 @@
 
 {% block app_content %}
     <div class="row">
-        <div class='well col-xs-8 col-sm-4'>
-            {{ wtf.quick_form(form, button_map={'submit': 'primary'}) }}
+        <div class="col col-xs-12 col-sm-6 col-md-4">
+        <div class='well'>
+
+        <form class="form" method="post" role="form" novalidate>
+
+        {{ form.hidden_tag() }}
+
+        {{ wtf.form_errors(form, hiddens="only") }}
+
+        <div class="form-group required {% if form.start_time.errors %}has-error{% endif -%}">
+            {{ form.start_time.label(class_="control-label") }}
+            <div class='input-group' id='start_time_group'>
+                <input name='start_time' id='start_time_' class="form-control" value="{{ form.start_time.data }}"/>
+                <span class="input-group-addon">
+                    <span class="glyphicon glyphicon-calendar"></span>
+                </span>
+            </div>
+            {% for error in form.start_time.errors %}
+            <p class="help-block">{{ error }}</p>
+            {% endfor %}
+        </div>
+
+        <div class="form-group required {% if form.length.errors %}has-error{% endif -%}">
+            {{ form.length.label(class_="control-label") }}
+            {{ form.length(class_="form-control") }}
+            {% for error in form.length.errors %}
+            <p class="help-block">{{ error }}</p>
+            {% endfor %}
+        </div>
+
+        <div class="form-group required">
+        {{ form.submit(class_="btn btn-primary") }}
+        </div>
+
+        </form>
+
+        </div>
         </div>
     </div>
 {% endblock %}
@@ -30,7 +65,7 @@
 
 <script type="text/javascript">
     $(document).ready(function() {
-        $('#start_time').datetimepicker({
+        $('#start_time_group').datetimepicker({
             locale: 'de',
             format: 'YYYY-MM-DD HH:mm',
             sideBySide: true