fix tests
fix #116
clarify document completion
fix mapping: german specific content should not be put into default collector (the one for all languages)
first version:
 - state gets read from nominatim
 - state is saved in elastic search index
 - state is considered in queries
 - state is attached in geojson result

 still to be tested
unified constants
verified, see https://github.com/twain47/Nominatim/blob/4cfeeb06ba828c94115f9496004a7a13cd8e1a03/tests/features/db/import/placex.feature#L163

refers to #102