by joachim: Fixed code style.
by joachim: Fixed api.php docs.
Issue #1960108 by joachim: Fixed 'create' resource trying to check a return value which doesn't exist for Core entities.
by joachim: Fixed entity_access() on entityreference field entities called with wrong entity type.
Issue #1948138 by joachim: Added entity_access() checks to the Entity Reference relationship resources.
Issue #1953108 by joachim: Changed 'index' resource query parameter to 'parameters' to match Services.
by joachim: Fixed whitespace.
Issue #1936472 by joachim: Added forward Services relationships for entityreference fields.
Issue #1911810 by joachim: Fixed multiple fields from one entity type to another overwriting the same resource name.
Issue #1911798 by joachim: Fixed entityreference fields' 'target_bundles' setting being used instead of entity type when defining relationships.