* Prefix most log messages with the IP address of the client.

* Log login success/failures uniformly

  Prior to this commit failed login attempts were not logged at all.

  Now successful logins are reported like this:

    Login successful for user "bruce"

  And failed logins are reported like this:

    Login failed for user "bruce"

Change-Id: Ibfd3a01a83c263b87dd669bcd685b3483f016df6
Reviewed-on: https://gerrit.franz.com:9080/12140
Reviewed-by: Ahmon Dancy <dancy@franz.com>
Reviewed-by: Kevin Layer <layer@franz.com>
Tested-by: Kevin Layer <layer@franz.com>