Summary: In/Direct Containers do not manage the membership triples of NonRdfSources.
Steps to reproduce:
* Create an ldp:NonRdfSource, say an image (img)
* Create an ldp:DirectContainer (dc), with membershipResource of img, and some hasMemberRelation (rel)
* Create a new resource (new) inside dc
* GET img/fcr:metadata
Expected Behavior: The fcr:metadata response to include the triple: img rel new
Observed Behavior: The triple does not appear in any representation
Remediation Requested: Either the container should reject the NonRDFSource as the object of membershipResource (boo!) or preferably the triple should be added to the fcr:metadata response, otherwise in contravention of LDP 184.108.40.206.