Allow for formatting perfStats header field in JSON.
Add PerfStats.getTotal(String), deprecate UIResults.getTotalCount().
Make PerfStats.OutputFormat public so that Spring can set property from string.
FIX PerfStats.getAllStats() writes count instead of total in JSON format. 
Write “null” if entry.isErr.
Avoid updating total stat more than once.
Merge branch 'perf-header' into ait-qa