Resubmission of final thesis should show correct date

If an examiner rejected a final thesis and the author resubmitted a thesis
to his supervisor so it can be sent to the examiner for a new round. When
that happened the feedback to the author was wrong, after a resubmission was
made and sent to the examiner the first thesis date 'Submitted to examiner' was
shown. This caused a lot of confusion. This happened because after the rejection
the date for when it was submitted to the examiner was not reset.

Now the date is reset and the feedback loop regarding dates is the same as when they first
send in their final thesis. In other words, when they resubmit their thesis they will not
see a 'Submitted to examiner' date until the supervisor actually resends the thesis to the
examiner. Then the date feedback will show up for the author with the correct date it was sent
to the examiner.

daisy-integration/src/main/java/se/su/dsv/scipro/integration/daisy/workers/RejectedThesisWorker.java

@@ -56,6 +56,7 @@ public class RejectedThesisWorker extends AbstractWorker {
                     if (supervisorGradingReport.getLastModified().before(rejectedDate)) {
                         supervisorGradingReport.setState(GradingReport.State.INITIAL);
                         supervisorGradingReport.setSubmitted(false);
+                        supervisorGradingReport.setDateSubmittedToExaminer(null);
                         supervisorGradingReport.setRejectionComment(thesisRejection.getMessage());
                     }
                 }