reporting cleanup (#1903)

- show form error when trying to load invalid user
- added non-breaking space to first table cells to allow copy&paste to excel
- added several css classes to allow customizations
- remove team assignment check for user selection

templates/reporting/layout.html.twig

@@ -7,7 +7,7 @@
 
 {% block main %}
     <div class="row">
-        <div class="col-md-12">
+        <div class="col-md-12" id="reporting-content">
             {% block report %}{% endblock %}
         </div>
     </div>