Draft: CSV export

Close #56

aleksis/apps/csv_import/forms.py

@@ -29,8 +29,7 @@ class CSVUploadForm(forms.Form):
 
 class CSVExportForm(forms.Form):
     school_term = forms.ModelChoiceField(
-        queryset=SchoolTerm.objects.all(),
-        label=_("Related school term"),
+        queryset=SchoolTerm.objects.all(), label=_("Related school term"), required=False
     )
     template = forms.ModelChoiceField(queryset=CSVTemplate.objects.all(), label=_("CSV template"))