improve datacite field mapping and import

Current version succeeded to import a random sample of 100000 records
(0.5%) from datacite.

The --debug (write JSON to stdout) and --insert-log-file (log batch
before committing to db) flags are temporary added to help debugging.

Add few unit tests.

Some edge cases:

a) Existing keys without value requires a slightly awkward:

```
titles = attributes.get('titles', []) or []
```

b) There can be 0, 1, or more (first one wins) titles.

c) Date handling is probably not ideal. Datacite has a potentiall fine
grained list of dates.

The test case (tests/files/datacite_sample.jsonl) refers to
https://ssl.fao.org/glis/doi/10.18730/8DYM9, which has date (main
descriptor) 1986. The datacite record contains: 2017 (publicationYear,
probably the year of record creation with reference system), 1978-06-03
(collected, e.g. experimental sample), 1986 ("Accepted"). The online
version of the resource knows even one more date (2019-06-05 10:14:43 by
WIEWS update).

2 files changed, 1 insertions, 0 deletions

diff --git a/python/tests/files/datacite_1k_records.jsonl.gz b/python/tests/files/datacite_1k_records.jsonl.gz
new file mode 100644
index 00000000..28ea6e37
--- /dev/null
+++ b/python/tests/files/datacite_1k_records.jsonl.gz
diff --git a/python/tests/files/datacite_sample.jsonl b/python/tests/files/datacite_sample.jsonl
new file mode 100644
index 00000000..dba3e267
--- /dev/null
+++ b/python/tests/files/datacite_sample.jsonl
@@ -0,0 +1 @@
+{"id":"10.18730/8dym9","type":"dois","attributes":{"doi":"10.18730/8dym9","identifiers":[{"identifier":"https://doi.org/10.18730/8dym9","identifierType":"DOI"},{"identifier":"ICDW 20791","identifierType":"Other"}],"creators":[{"name":"GLIS Of The ITPGRFA","affiliation":[]}],"titles":[{"title":"Triticum turgidum L. subsp. durum (Desf.) Husn. 97090"}],"publisher":"International Centre for Agricultural Research in Dry Areas","container":{},"publicationYear":2017,"subjects":[{"subject":"Plant Genetic Resource for Food and Agriculture"}],"contributors":[{"name":"International Centre For Agricultural Research In Dry Areas","affiliation":[]}],"dates":[{"date":"1986","dateType":"Accepted"},{"date":"1978-06-03","dateType":"Collected"},{"date":"2017","dateType":"Issued"}],"language":"en","types":{"ris":"GEN","bibtex":"misc","citeproc":"article","schemaOrg":"CreativeWork","resourceType":"PGRFA Material","resourceTypeGeneral":"PhysicalObject"},"relatedIdentifiers":[{"schemeUri":"http://www.fao.org/plant-treaty/areas-of-work/global-information-system/descriptors","schemeType":"XML","relationType":"HasMetadata","relatedIdentifier":"https://ssl.fao.org/glisapi/v1/pgrfas?doi=10.18730/8DYM9","relatedIdentifierType":"URL","relatedMetadataScheme":"GLIS Descriptors"},{"schemeUri":"http://rs.tdwg.org/dwc/terms/guides/text/index.htm","schemeType":"DwC-A","relationType":"HasMetadata","relatedIdentifier":"https://ssl.fao.org/glisapi/v1/pgrfas?_format=dwc&doi=10.18730/8DYM9","relatedIdentifierType":"URL","relatedMetadataScheme":"Darwin Core Archive"}],"sizes":[],"formats":[],"version":null,"rightsList":[],"descriptions":[{"description":"Plant Genetic Resource.<br>Taxonomy: Triticum turgidum L. subsp. durum (Desf.) Husn.<br>Common name(s): Wheat<br>Conserved by: International Centre for Agricultural Research in Dry Areas (ICARDA), Lebanon<br>Local sample unique identifier: 97090<br>Method of creation: Acquisition<br>Date: 1986<br>Biological status: Traditional cultivar/landrace<br>Other identifiers: ICDW 20791<br>MLS status: Included<br>Historical: No","descriptionType":"Abstract"}],"geoLocations":[{"geoLocationPlace":"Collecting site","geoLocationPoint":{"pointLatitude":"35.5","pointLongitude":"23.7333"}}],"fundingReferences":[],"url":"https://ssl.fao.org/glis/doi/10.18730/8DYM9","contentUrl":null,"metadataVersion":3,"schemaVersion":"http://datacite.org/schema/kernel-4","source":"mds","isActive":true,"state":"findable","reason":null,"created":"2017-11-11T12:26:01.000Z","registered":"2017-11-11T12:26:02.000Z","published":"2017","updated":"2019-08-02T16:34:56.000Z"},"relationships":{"client":{"data":{"id":"fao.itpgrfa","type":"clients"}}}}