Write test to export sample mappings

[nichtich]

After #90, when the list of concept schemes includes notationExamples for each, a script should run test queries against web service and cli with these examples.

For instance P5748 of Q29938469 (Basisklassifikation) has example notation 42.13, at https://www.wikidata.org/wiki/Q7202 so these should return same mapping:

1. Query mappings

wdjskos m http://uri.gbv.de/terminology/bk/42.13
wdjskos -s http://bartoc.org/en/node/18785 m http://www.wikidata.org/entity/Q7202 - 

2. Convert mapping to JSKOS and back

The mapping should also be convertible to Wikidata claim with wdjskos i - this should be tested by getting raw Wikidata JSON and comparing the claim round-tripped from Wikidata to JSKOS and back.