CLT-141 Job:show doesn't show result for Presto queries

Changes:
- added presto to list of supported engine types as
  reported by the client ruby library
- show all 4 types of engines supported currently:
  hive, pig, impala, presto
- hide some fields from the job:show output when
  the job type doesn't match any of the supported
  job types: typically that happens for bulk_import_perform
  jobs.
- changed field key from 'Result' (which appears twice)
  to 'Output'
- not showing stderr or cmdout sections if the corresponding
  output is empty