Fix CSRF issues in svx form

Set date formats
Add DataIssue model and add errors to it to allow us to give people a list of
stuff to fix

core/admin.py

@@ -139,6 +139,7 @@ admin.site.register(SurvexStation)
 admin.site.register(SurvexScansFolder)
 admin.site.register(SurvexScanSingle)
 
+admin.site.register(DataIssue)
 
 def export_as_json(modeladmin, request, queryset):
     response = HttpResponse(content_type="text/json")