toy build for Global IO Manager thread pool etc

Change-Id: Ide71f9507bd127525b9721eaeaa7b7418f85857c
Reviewed-on: http://review.couchbase.org/28538
Reviewed-by: Sundararaman Sridharan <sundar.sridharan@gmail.com>
Tested-by: Sundararaman Sridharan <sundar.sridharan@gmail.com>