Updated rcperf to uniformly spread keys on servers.
Updated rcperf to uniformly spread keys on servers.

Now rcperf multiread tests will spread out keys evenly among servers, instead of
ramdonly.

ellitron/RAMCloudTools,jdellithorpe/RAMCloudUtils,jdellithorpe/RAMCloudTools,ellitron/RAMCloudTools,jdellithorpe/RAMCloudUtils,ellitron/RAMCloudTools,jdellithorpe/RAMCloudUtils,jdellithorpe/RAMCloudTools