Adding start_time and end_time to array per request

Per analytics request.  Also updated docs in https://github.com/opscode/client-docs/commit/88f7369d1d8a7ffc26c751f5a078d6d0d43cbb5f

\cc @sersut @mcquin @metadave 
I also realized that `end_time` was not set on the run_status until right before `run_completed` or `run_failed` is called