Fix test_bucket_acl tests

[lincolnthomas]

The test_bucket_acl() function in testcases/cloud_user/s3/bucket_tests.py fails, for a number of reasons, and was commented out of the tests list in __main__. We would like it to be fixed.

[lincolnthomas]

Fixed:

1. Added READ_ACP to the expected grants for the log_delivery S3 group.
2. Re-enabled the authenticated-read canned ACL test, which passes with no changes.
3. Skipped the "bucket-owner-read" and "bucket-owner-full-control" canned ACLs which only apply to objects, not buckets.

[lincolnthomas]

Also:
4. Commented out a test that tried to added a READ grant to the owner, who already has FULL_CONTROL. Not a useful test. See the code comments.