feature/meta flat: counts rm

[bwalsh]

This PR adds commands to meta flat

[bwalsh]

e.g.

• query

  $ aced_submission meta flat counts --project_id aced-Alzheimers
  patient 287
  observation 192086
  file 730

• rm observations for project

  $aced_submission meta flat rm --project_id aced-Alzheimers  --index observation
  deleting, waiting up to 5 min. for response
  observation {'took': 17, 'timed_out': False, 'total': 0, 'deleted': 192086, 'batches': 0, 'version_conflicts': 0, 'noops': 0, 'retries': {'bulk': 0, 'search': 0}, 'throttled_millis': 0, 'requests_per_second': -1.0, 'throttled_until_millis': 0, 'failures': []}

• requery

  $aced_submission meta flat counts --project_id aced-Alzheimers
  patient 287
  observation 0
  file 730