setting vm-swappiness to 0

Change-Id: Ie7dc2ee34251ddfa149d28f37e6e59db7031b0a9
Reviewed-on: http://review.couchbase.org/31218
Reviewed-by: Aruna Piravi <aruna@couchbase.com>
Tested-by: Aruna Piravi <aruna@couchbase.com>