Merge changes I7e64747e,I07c6df6d,I9c465648,Ib3de9f4f,Ib4df4f10, ...

* changes:
  Delete the last iptables commands in BandwidthController.
  Switch costly alerts to iptables-restore.
  Add a test for costly alerts.
  Minor improvements to shared quota error handling.
  Convert set*Quota to use iptablesRestore.
  Refactor interface quota code before moving to iptables-restore.
  Remove superfluous quota rule delete commands.