Allow disabling acl (canned_acl as nil) for Google Cloud Storage compatibility #50
Description
I know that the s3 output is explicitely advertised as not compatible with other services, but it is much more flexible that the google cloud storage output plugin, so I'm using it instead.
It is working as intended, but I had to enable ACLs (or rather disable uniform bucket access) in my bucket, because there isn't an option to disable ACLs (google's API refused to accept an ACL returning "Invalid argument" as a response). Would it be ok to allow the canned_acl option to be nil?