Add support for hash URIs as membership resources about lakesuperior HOT 1 OPEN

Furthermore, when creating a Direct Container whose membership resource is a self-referential hash URI (e.g. the DC is http://localhost:8000/ldp/dc and the membership resource is http://localhost:8000/ldp/dc#it), POSTing a child resource returns a 404 Not Found.

i.e. given this DC at http://localhost:8000/ldp/dc:

PREFIX dcterms: <http://purl.org/dc/terms/>
PREFIX ldp: <http://www.w3.org/ns/ldp#>

<> dcterms:title "Direct Container" ;
    ldp:membershipResource <#it> ;
    ldp:hasMemberRelation dcterms:relation .

I cannot POST a child resource to this container, because I get this error:

HTTP/1.1 404 NOT FOUND
Server: gunicorn/19.7.1
Date: Wed, 25 Apr 2018 17:48:52 GMT
Connection: keep-alive
Content-Type: text/html; charset=utf-8
Content-Length: 60

Resource /dc#it not found.

from lakesuperior.