Added cbauditd

Not strictly necessary since the default is "membase" anyway, but for completeness.

Change-Id: I504c890da6661383beec174ce55246abee6c408b
Reviewed-on: http://review.couchbase.org/42563
Reviewed-by: Chris Hillery <ceej@couchbase.com>
Tested-by: Chris Hillery <ceej@couchbase.com>