Add 'q' option for quiet operation

Signed-off-by: Stratos Karafotis <stratosk@semaphore.gr>
Makefile: Add pre-requisites

Signed-off-by: Stratos Karafotis <stratosk@semaphore.gr>
sbench: Add empty line

Signed-off-by: Stratos Karafotis <stratosk@semaphore.gr>
sbench: Sleep time in usec

For more accuracy

Signed-off-by: Stratos Karafotis <stratosk@semaphore.gr>