Add a sleep in the NmapProcess.__wait.  This has the down side of reducing the resolutionof our polling for output from or completion of the command, but has the benefit of greatly reducing CPU utilization in libnmap.  Before this change we would sit at 100% CPU in libnmap while a long running scan was in progress.
Merge pull request #21 from warnerpr-cyan/master

Add a sleep in NmapProcess.__wait to reduce CPU overhead