Bump src/cloud_controller_ng

Bump cloudfoundry/cloud_controller_ng:
  Graeme Davison and James Myers:
     Merge remote-tracking branch origin/pr/223 ( Travis created: https://travis-ci.org/cloudfoundry/cloud_controller_ng/builds/32495535 )
  David Sabeti and Rob Dimsdale:
     Return API errors when instance creation returns with an unexpected syslog_drain_url [finishes #74403130] ( Travis started: https://travis-ci.org/cloudfoundry/cloud_controller_ng/builds/32491685 )
  Michael Fraenkel:
     Prevent users from viewing quotas ( Travis Unknown )