Add example how to produce statistics of field-values

See hbz/lobid#91

This example produces a list with occurences of values residing
in the nwbib fields "700 96/97/99" (spatial literals).
Merge branch 'statistics' into integrationTest-remove-osm-lookup

Conflicts:
	lodmill-rd/src/test/java/org/lobid/lodmill/MabXmlElasticsearch2FieldValueStatistics.java