Add cbauditd

Change-Id: Iaba498999a1d25ec37f27120d182b5ae04f57e4c
Reviewed-on: http://review.couchbase.org/43354
Reviewed-by: Trond Norbye <trond.norbye@gmail.com>
Tested-by: Trond Norbye <trond.norbye@gmail.com>