Benchmark Demo Performance Improvements

[stanbrub]

Currently, when the Benchmark Demo is run, it takes about 20 seconds. That's too long for a demo.
Issues:

• The demo server is Google. The NFS server is Google. The pipe between them appears to be slow. (Throttling?)

• The tables are loaded one-by-one rather than in parallel

• Load the CSV the files in parallel, at least for the same table

• Compress the data in GCloud Gzip CSV for Benchmark Cmd Line Results #177

Notes:

• On the demo server, reading csv.gz vs csv does not improve demo performance. NFS appears to be the problem.
• If you run the demo when the worker first spins up, the demo takes 20 sec. Run it subsequently, and it takes 2-3 secs.