Drop support for syslog logger

Change-Id: Ibb077a255562f7b66a7e25c7959b3c5712ab053b
Reviewed-on: http://review.couchbase.org/26922
Reviewed-by: Trond Norbye <trond.norbye@gmail.com>
Tested-by: Trond Norbye <trond.norbye@gmail.com>