Fix authenticated CORS requests (#36) * refactor: switch from the deprecated request package to std fetch() * fix: add some heuristics for RDF fetching - non-localhost URIs get upgraded to HTTPS - CORS failing requests get retried with a CORS proxy without credentials - requests URIs ending with .ttl are parsed as Turtle not RDF/XML * fix: update OSLC links Signed-off-by: Andrew Berezovskyi <andriib@kth.se>