Bump src/cloud_controller_ng, src/collector, src/dea_next

Bump cloudfoundry/cloud_controller_ng:
  Dan Lavine and Serguei Filimonov:
     Bump nats in hope of balancing between servers better ( Travis Success: https://travis-ci.org/cloudfoundry/cloud_controller_ng/builds/44239398 )
  Joseph Palermo and Sujoy Basu:
     Clear the experimental flag from the copy app bits API docs ( Travis Success: https://travis-ci.org/cloudfoundry/cloud_controller_ng/builds/44157649 )
  David Sabeti and Ketan Deshpande:
     Add missing request key to event metadata ( Travis Success: https://travis-ci.org/cloudfoundry/cloud_controller_ng/builds/44150204 )
Bump cloudfoundry/collector:
  Dan Lavine and Serguei Filimonov:
     Bump nats in hope of balancing between servers better ( Travis Success: https://travis-ci.org/cloudfoundry/collector/builds/44239145 )
Bump cloudfoundry/dea_ng:
  Michael Fraenkel:
     Update NATS - distribute initial connection ( Travis Success: https://travis-ci.org/cloudfoundry/dea_ng/builds/44239074 )
  Joseph Palermo and Sujoy Basu:
     DEA sends nats heartbeat even when there are no running instances This keeps HM9000 from thinking there are problems. ( Travis Success: https://travis-ci.org/cloudfoundry/dea_ng/builds/44156921 )