Use sigar to determine number of CPU and disk type

Change-Id: Id8b93b16266f53259068216dd6ae1afa9997006c
Reviewed-on: http://review.couchbase.org/30552
Reviewed-by: Sundararaman Sridharan <sundar.sridharan@gmail.com>
Tested-by: Sundararaman Sridharan <sundar.sridharan@gmail.com>