#144 Report improved

* fixes bug in egon_export.py where missing payment date would result in non writing of gml
* fixes bug in egon_export.py which occured due to extension of parcel data fetching
* updates unavailable.html report content, such that users will understand why a recorded entry might not be visible, yet

templates/report/unavailable.html

@@ -7,7 +7,9 @@
         <hr>
         <p class="lead">
             {% blocktrans %}
-            The data you want to see is not recorded and might still be work in progress. Please come back another time.
+            The data you want to see is not recorded and might still be work in progress or the legal binding date has
+            not been reached yet. We can not publish this report as long as revocations could occur.
+            Please come back later.
             {% endblocktrans %}
         </p>
     </div>