Merge changes Ic2b692ef,Iaa8daba0,Ie39a6eac,I8e159405,I8224b4cc

* changes:
  Properly report failure in runIptablesAlertCmd.
  Move enableChildChains to iptables-restore.
  Add test coverage for enableChildChains.
  Move runIptablesAlert{,Fwd}Cmd to iptables-restore.
  Add test coverage for IptablesAlert{,Fwd}Cmd.