Remove acl header

[SamVerschueren]

Hi @cworsley4

You did a PR #44 in gulp-s3 removing the acl header. Why isn't this removed in your fork :p?

I don't want my files to be publicly available. I want to set it via the bucket policy instead.

Kind regards

[cworsley4]

Well, I submitted a few PRs to gulp-s3 none of which actually got acknowledged or merged. I guess I forgot to make that change in my fork. I would welcome a PR if you're so inclined.