Bump src/cloud_controller_ng

Bump cloudfoundry/cloud_controller_ng:
  Eric Malm:
     Add StenoConfigurer helper for consistent Steno configuration ( Travis started: https://travis-ci.org/cloudfoundry/cloud_controller_ng/builds/20179552 )
     Fix Steno test pollution from re-initialization ( Travis Unknown )
     Add RequestJob wrapper to preserve VCAP-Request-ID on async jobs ( Travis Unknown )
  Karl Isenberg:
     Add logging to all async jobs; fix thread-scoped request_guid test pollution ( Travis Unknown )
     Move Steno request_guid into VCAP::Request.current_id setter ( Travis Unknown )
Bump src/cloud_controller_ng

Bump cloudfoundry/cloud_controller_ng:
  Ruth Byers:
     Minor refactor ( Travis started: https://travis-ci.org/cloudfoundry/cloud_controller_ng/builds/20180299 )
     Unset the buildpack via passing an empty string ( Travis Unknown )