Bump src/cloud_controller_ng

Bump cloudfoundry/cloud_controller_ng:
  Aram Price:
     Hoist timeout values to the top, trim comments ( Travis created: https://travis-ci.org/cloudfoundry/cloud_controller_ng/builds/22065172 )
  Ruth Byers:
     Add more logging and DRY up router deregister ( Travis Unknown )
     Clean up in drain script ( Travis Unknown )
  Abhijit Hiremagalur:
     Split responsibilities of calculating position and shifting ( Travis Success: https://travis-ci.org/cloudfoundry/cloud_controller_ng/builds/22063632 )
     Positioner no longer know about Buildpack.db ( Travis Unknown )
     Be defensive about hash key style ( Travis Unknown )
     Reduce knowledge about the db in positioner ( Travis Success: https://travis-ci.org/cloudfoundry/cloud_controller_ng/builds/22055319 )
     Encapsulate shift_to_position in update ( Travis Unknown )
     Extract BuildpackPositioner ( Travis Unknown )
     Need to call destroy to exercise after_destroy ( Travis Unknown )
     Remove dead code related to prioritized buildpacks ( Travis Unknown )