radosgw-admin.py: add test of deleting bucket with objects.

Signed-off-by: caleb miles <caleb.miles@inktank.com>
radosgw-admin.py: add test of deleting user with data.

Signed-off-by: caleb miles <caleb.miles@inktank.com>
radosgw-admin.py: Increase test coverage to current admin feature set.

Signed-off-by: caleb miles <caleb.miles@inktank.com>
Merge remote-tracking branch 'origin/wip-3634'