Bump src/cloud_controller_ng

Bump cloudfoundry/cloud_controller_ng:
  Alex Suraci and Phan Le:
     fix flaky death spec ( Travis started: https://travis-ci.org/cloudfoundry/cloud_controller_ng/builds/11569084 )
     Remove sqlite3 build on Travis until we figure out the slowness ( Travis Failed: https://travis-ci.org/cloudfoundry/cloud_controller_ng/builds/11568755 )
     Renamed blob_store to blobstore ( Travis finished: https://travis-ci.org/cloudfoundry/cloud_controller_ng/builds/11562430 )
     Protect the droplets and build pack cache upload and download urls by basic auths. ( Travis finished: https://travis-ci.org/cloudfoundry/cloud_controller_ng/builds/11521972 )
  phanle:
     Moving things around in blobstore test. Gradually remove the use of blobstore.files as it should not be exposed. ( Travis finished: https://travis-ci.org/cloudfoundry/cloud_controller_ng/builds/11554063 )
     Renamed key_from_sha1 to partitioned_key ( Travis Success: https://travis-ci.org/cloudfoundry/cloud_controller_ng/builds/11537616 )
     Fix the wrong droplet keys get generated. ( Travis Unknown )
  Chris Brown and Julz Friedman:
     Test classes rather than equality in billing events ( Travis Failed: https://travis-ci.org/cloudfoundry/cloud_controller_ng/builds/11532860 )
     Remove test pollution from new Billing Event spec ( Travis finished: https://travis-ci.org/cloudfoundry/cloud_controller_ng/builds/11529858 )
     Let Sequel know about the old BillingEvent classes ( Travis finished: https://travis-ci.org/cloudfoundry/cloud_controller_ng/builds/11521204 )