print out more metadata

[VladimirAlexiev]

VladimirAlexiev#1 implements this:

• print out more metadata:
  dct:created, dct:modified, rdfs:seeAlso, dct:source, foaf:homepage, skos:definition (treated same as rdfs:comment), skos:scopeNote, skos:example
• Don't prefixize links to Google Docs eg https://docs.google.com/document/d/1dhMOTlIOC6dOK_jksJRX0CB-GIRoiYY6fWtCnZArUhU/edit
  to avoid ugly Namespace Declarations eg random-prefix -> https://docs.google.com/document/d/1dhMOTlIOC6dOK_jksJRX0CB-GIRoiYY6fWtCnZArUhU/
  (f:isPrefixeable())

@essepuntato I don't know how to make this PR in your repo instead of mine without mixing it up with the pending PR #13 we have. So please review and comment on the above PR, and once we finalize #13, I'll merge both PRs or resubmit it against the new master.
Thanks!

[VladimirAlexiev]

TODO:

• update documentation (mention the above props)
• update fr, it.xml (I added all needed labels, but all are in EN)