Re-implement SlowMemcpyWorkload & SlowMemcpyDataset & rename

[JackKelly]

Vincent suggests:

• one-pass_out-of-core_batchwise_low-latency <-- this is what I proposed, locally from SSD
  • access profile 1, profile 2, profile 3, ... (various advanced indexing profiles while doing the one-pass)
• one-pass_out_of_core_batchwise_high-latency <-- this would be the same, over the network
  • access profile 1, profle 2, profile 3, .... (various advanced indexing profiles while doing the one-pass)
• parallel-map-reduce_local_low-latency <-- this would be map-reduce but on a single computer
• parallel-map-reduce_clustered_high-latency <-- this would be map-reduce but in a clustered environment

xref #5 #6 #7