docs: fix storage jsdoc

Somewhere along the way with the ACL PR, the docs went from perfect to busted -- see the ACL section of https://googlecloudplatform.github.io/gcloud-node/#/docs/v0.11.0/storage/bucket. `add` should be `acl.add`. The acl.default methods are also completely missing.

This PR fixes that by using aliases in the storage/acl.js file, fixes some doc wording, and returns the true value to the dummy doc placeholder variables.