Update dependencies

Among others, this updates minio-go, so that the new "eu-west-3" zone
for AWS is supported.

vendor/cloud.google.com/go/internal/version/version.go

@@ -26,7 +26,7 @@ import (
 
 // Repo is the current version of the client libraries in this
 // repo. It should be a date in YYYYMMDD format.
-const Repo = "20170928"
+const Repo = "20180118"
 
 // Go returns the Go runtime version. The returned string
 // has no whitespace.