Bump src/cloud_controller_ng

Bump cloudfoundry/cloud_controller_ng:
  Michael Fraenkel:
     Remove unnecessary and deprecated VCAP_APPLICATION variables ( Travis started: https://travis-ci.org/cloudfoundry/cloud_controller_ng/builds/44860491 )
  David Sabeti and Michael Maximilien:
     Return 504 instead of 408 when call to broker times out ( Travis Success: https://travis-ci.org/cloudfoundry/cloud_controller_ng/builds/44640194 )
  David Sabeti, Ketan Deshpande and Whitney Schaefer:
     Grouping query tests to make them easier to read ( Travis Success: https://travis-ci.org/cloudfoundry/cloud_controller_ng/builds/44637849 )
  David Sabeti and Whitney Schaefer:
     Fix IN clause behavior for foreign keys [finishes #78842212] ( Travis Unknown )
     Refactor query.rb and backfill tests for error cases ( Travis Unknown )