Merge pull request #21 from satra/enh/rdf

updating rdf branch with upstream commits

Many thanks to @satra!
Merge pull request #25 from satra/enh/rdf

Enh/rdf
Merge pull request #28 from satra/enh/rdf

fix: save prov:label as rdfs:label during rdf export
keep the timezone when parsing datetime from JSON
Merge pull request #29 from jdcourcol/master

keep the timezone when parsing datetime from JSON
fix: resolved conflict