Added option --lock-directory so that you can now syncronize several mysqlslap processes across several machines. Not perfect yet.

Added --slave option if you are trying to syncronize around one server using the lock-directory option plus NFS. 

Added options to allow you to run several concurrency runs in one call. aka --concurrency="1, 8, 64, 128"

Time collection is now done in a finer grain manner, and is linked to the sync call (doesn't count the cost of the blocked processes that are setup to run).