Merge "Add DHCP error event class and record DHCP errors." into nyc-dev
am: fc18b6f

* commit 'fc18b6f3608d87f3dc53cda8d8db30636c92d6e9':
  Add DHCP error event class and record DHCP errors.

Change-Id: I5b9ef8b191ab0ef4349ed00c1d8f548393aba368