MB-100: revised cap confs

Change-Id: Ie5dd9d37f2e854cf8429de3d6655591036a06310
Reviewed-on: http://review.couchbase.org/23927
Reviewed-by: Ronnie Sun <ronnie@couchbase.com>
Tested-by: Ronnie Sun <ronnie@couchbase.com>
MB-100: revised water mark defaults

Change-Id: If6318fa07b02bf202d9f623f16ca45196952951e
Reviewed-on: http://review.couchbase.org/23928
Reviewed-by: Ronnie Sun <ronnie@couchbase.com>
Tested-by: Ronnie Sun <ronnie@couchbase.com>