Add benchmarks

From @adriancole on November 17, 2015 3:21

Some aspects of code need to be benchmarked as they will be run a lot.

Here's some ideas... feel free to contribute!

For each scenario, use traces of 1-5 depth and 10-200 width, where spans range from local to remote w/up to 2KB annotation sizes.

Library Microbenchmarks:

• thrift and json codec
• time skew adjustment

Integration Benchmarks (ex server running against each spanstore impl)

• accepts/second for 1, 10, 100 length spans in json vs thrift
• at rest size of 10K - 1M traces:
• service/span name query latency
• duration query latency
• dependency query latency

Copied from original issue: openzipkin/zipkin-java#45