Bump cli to 6.6.1

- in blobs
- in docker pipeline image
- bump acceptance-tests

Bump :
  Trevor Ackerman and Zach Robinson:
     Use cli commands for env var groups added in cli 6.6.1
Bump src/cloud_controller_ng

Bump cloudfoundry/cloud_controller_ng:
  Michael Fraenkel:
     User visibility for Orgs and Spaces ( Travis started: https://travis-ci.org/cloudfoundry/cloud_controller_ng/builds/36394180 )