Bump src/cloud_controller_ng

Bump cloudfoundry/cloud_controller_ng:
  Onsi Fakhouri:
     Generate environment variables in CC for diego staging message ( Travis Success: https://travis-ci.org/cloudfoundry/cloud_controller_ng/builds/19285299 )

Signed-off-by: Maria Shaldibina <mariash@pivotallabs.com>