Fix character encodings in listings

The php-json-ld and LibRDF libraries handle utf-8 string differently.
LibRDF assumes the old N-Triples serialization, in which umlauts are
encoded using their hex-value whereas php-json-ld processes N-Triples as
utf-8.

Fixes EDOZWO-187
Extend utf-8 hex mapping

Fixes EDOZWO-187
Implement just in time import

Until recently, listings where generated based on the drupal-internal
representations of resources. With listing now being based on
elasticsearch, we can load resources from the API just in time, i.e.
when a full view of the resource is requested. This will probably also
make the bulk import needless.

FIXES EDOZWO-238
Merge branch '0.2.0' into test