fix(hydra): resolve related class when hydra_prefix is false (#166)

When hydra_prefix is not set to true, owl:onProperty uses bare "member"
  which jsonld.expand resolves via @vocab (e.g. "http://localhost/docs.jsonld#member")
  instead of "http://www.w3.org/ns/hydra/core#member". This caused Strategy 1
  in findRelatedClass to fail. For read-only resources without a POST operation,
  Strategy 2 also fails, resulting in "Cannot find the class related to..." errors.

  Relax the onProperty check from exact match to endsWith("#member") so both
  the correct hydra IRI and the @vocab-expanded IRI are accepted.

  Closes #147

Author: soyuka