server: tools + libxtreemfs for Java: Disable periodic refresh in used...

server: tools + libxtreemfs for Java: Disable periodic refresh in used TimeSync object to get rid of granularity warning.

The warning was: "The granularity of the renewed local time could not be guaranteed since it took longer to retrieve the latest local time (xxx ms) than configured (local_clock_renewal = 50). Maybe the system is under high I/O load and therefore scheduling threads takes longer than usual?"