Refactor test_s3_acl

This patch introduces generate_s3acl_environ() function
for refactoring of test_s3_acl. It registers necessary verbs against
to both a bucket and an object which keep ACL information for testing.

It achieves really good portability to make s3_acl testing environment
for other test cases so that What we have to do for s3_acl testing is
just calling generate_s3acl_environ() before testing.

Change-Id: I3f5d0d9bae021513d63b0ca35f015241873e3fd5