Toybuild for Global IO Manager thread pool etc

- edit

Change-Id: Id90fa4fa0f25b3309308c1b9218d3f08bb57e464
Reviewed-on: http://review.couchbase.org/28558
Reviewed-by: abhinav dangeti <abhinav.dangeti@gmail.com>
Tested-by: abhinav dangeti <abhinav.dangeti@gmail.com>