\SMW\DISerializer is in fact a \SMW\Serializers\QueryResultSerializer

DISerializer was never a "real" DI serializer and only used to
serialize QueryResult objects.

We also don't want to expose any specific method to the "outside world"
and instead have the SerializerFactory manage the SerializerInterface.

Change-Id: Ie234128e5ae7f0c72e619837cabdddb786958674
Merge "\SMW\DISerializer is in fact a \SMW\Serializers\QueryResultSerializer"