Remove autotune and latencytarget from async benchmarks; add more
percentile latency statistics and histogram in final report (default
for sync benchmarks, and when latencyreport enabled for async).
Add histogram to JDBC benchmarks and json example. Adjust bin height.
drop latencyreport from run scripts and add some comments
Merge pull request #553 from VoltDB/ENG-4305

ENG-4305: remove auto-tuning, add histogram for examples