Unify ACL handling between storage and bigquery

[tseaver]

From: #986 (comment)

The notion of ACLs might be pertinent for other discovery-based APIs, too (e.g., why does pubsub not have it?)

[dhermes]

@tseaver Is this ever going to happen? (I.e. is it feasible?)

[tseaver]

Because storage has separate APIs for its ACLs, it may not be feasible to unify the two.

[dhermes]

Can we move from "may not" to "will" or "won't" and then close this our (it it's "won't") or commit to it.

[tseaver]

I'd say "let's not".