[Ur] TechEmpower Benchmarks

[escalier at riseup.net]

The final preview results have been posted:

http://www.techempower.com/benchmarks/previews/round8/

These is pretty much the official result set except that some anomalous
results will be filtered out before the official posting.

Obvious improvements that occur to me for next round:
  - Create a quiet or verbose flag so that the all the stdout logging is
avoidable (e.g. "Handling connection with thread #1. Serving URI
/json....") The test runners require stdout to be piped to a file so it
can't just be `/dev/null`ed.
  - Create an alternate configuration that places Ur/Web behind a frontend
like Nginx