Significant improvements to benchmark report

- Added % change to performance regressions/improvements table
- Automatic extraction of Impala version from runtime profiles
- Execution summary row will not be printed if max time is < 100ms or < 2% of the overall runtime
- Failed queries are ignored
- First result is discarded for each query
- Geometric mean was added to summary
- Improved handling of multiple workloads in a single JSON file
- Improved handling of the case when queries are different in results and reference results
- Works well for single client runs. Additional work is needed to handle multiple client runs well.

Change-Id: Ice7b9cc4fd7502a448d35ace10fbcef183df1769
Reviewed-on: http://gerrit.sjc.cloudera.com:8080/4210
Reviewed-by: Ishaan Joshi <ishaan@cloudera.com>
Tested-by: jenkins