Index reconfiguring for better kibana-stats

[dr0i]

Result of #66.
To create nice stats the more index fields be typed as number (or even more accurate: date) the better.
See ES-docs for possible types. There is no need to change the format of the values e.g. of the field dateOfBirth - it seems to be sufficient to just configure the index to:

"type": "date_range" "type": "date",
"format": "yyyy-MM-dd"

(https://www.elastic.co/guide/en/elasticsearch/reference/5.6/date.html)

I would say that all fields starting with date are reasonable date_range date candidates.

[fsteeg]

The problem is that many dates in lobid-gnd have non-date values (like [19XX], [?], [XXXX], [20.] etc., see dateOfBirth aggregation in http://lobid.org/gnd/search?q=*&format=json), which would cause indexing errors if they were set as date (I guess).

[dr0i]

Correct, it would result in MapperParsingException, so we have to make sure that the value of date is valid. See hbz/lobid-resources#871 for details how this was done for lobid-resources.

[acka47]

Closing.