Added TableImageSplitter.
Added TableImageSplitter.

Utility for splitting table image files generated by the
TableDownloader.

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