Bump src/cloud_controller_ng

Bump cloudfoundry/cloud_controller_ng:
  Abhijit Hiremagalur:
     Remove rack-timeout completely ( Travis created: https://travis-ci.org/cloudfoundry/cloud_controller_ng/builds/18143811 )
  phanle:
     Remove unused gems ( Travis started: https://travis-ci.org/cloudfoundry/cloud_controller_ng/builds/18044452 )