Check for absolute match scores in Elasticsearch

[acka47]

With @literarymachine and @wetneb, we discussed elasticsearch scoring and match information of a reconciliation endpoint in a pre-WikidataCon meeting in Berlin. @literarymachine said that Elastiscearch scores would usually be relative with regard to the other hits in the index and indicated that there might be a way to get an absolute score as well which would be very valuabel for reconciliation. We should take a look into this at some point.