Added execution summary, modified benchmark to handle JSON

- Added execution summary to the beeswax client and QueryResult
- Modified report-benchmark-results to handle JSON and perform
  execution summary comparison between runs
- Added comments to the new workload runner

Change-Id: I9c3c5f2fdc5d8d1e70022c4077334bc44e3a2d1d
Reviewed-on: http://gerrit.ent.cloudera.com:8080/3598
Reviewed-by: Taras Bobrovytsky <tbobrovytsky@cloudera.com>
Tested-by: jenkins