message: Upgrade API dependencies googleapis, gogoproto, prometheus, opencensus
diff: -GOOGLEAPIS_SHA = "5c6df0cd18c6a429eab739fb711c27f6e1393366" # May 14, 2017
  -GOGOPROTO_SHA = "1adfc126b41513cc696b209667c8656ea7aac67c" # Feb 2, 2018
  -PROMETHEUS_SHA = "6f3806018612930941127f2a7c6c453ba2c527d2" # Nov 02, 2017
  -OPENCENSUS_SHA = "993c711ba22a5f08c1d4de58a3c07466995ed962" # Dec 13, 2017
  +GOOGLEAPIS_SHA = "d642131a6e6582fc226caf9893cb7fe7885b3411" # May 23, 2018
  +GOGOPROTO_SHA = "1adfc126b41513cc696b209667c8656ea7aac67c" # v1.0.0
  +PROMETHEUS_SHA = "99fa1f4be8e564e8a6b613da7fa6f46c9edafc6c" # Nov 17, 2017
  +OPENCENSUS_SHA = "ab82e5fdec8267dc2a726544b10af97675970847" # May 23, 2018
  PGV_GIT_SHA = "9f600c2cd2d7031fdc8e25e1c9f5ad81c8cab4fe"
  