Inform user we are working in the background

Print a message about astakos-quota calculating all user quotas,
which on a big system takes some time.

snf-astakos-app/astakos/im/management/commands/astakos-quota.py

@@ -115,6 +115,7 @@ class Command(BaseCommand):
     @transaction.commit_on_success
     def run(self, sync):
         try:
+            self.stderr.write("Calculating all quotas...\n")
             return sync_all_users(sync=sync)
         except BaseException, e:
             logger.exception(e)