`tryParent` in acl.js does not stop before trying to fetch https://

tryParent is a recursive function that takes a URL (e.g. https://foo.com/bar/baz) and tries to find an ACL for that resource by looking at its parent if none are found initially (e.g. https://foo.com/bar/ --> https://foo.com/).

There are a couple of problems with this:

1. Right now there is a bug that makes it also check https://. We need to stop the recursive function before this happens and give the appropriate error. (There should always be a root ACL, but errors might occur still.)
2. It will call tryParent if no triples for acl:default are found (https://github.com/solid/solid-ui/blob/master/src/acl.js#L359). This would mean that even though an ACL resource are found, the code will still look for another parent ACL resource, which I think goes against point 2 in https://github.com/solid/web-access-control-spec#acl-inheritance-algorithm.