Change metadata handling

[miselico]

Currently the CEUR-WS website is based on static html. The metadata is encoded in the static html.
For the future it would be nice to still have static html but the compilation process should go from a property "data structure" e.g. a tree or graph based approach using JSON, XML, a database of whatever fits. this would also allow easier creation of other formats.

[WolfgangFahl]

Example: have a separate landing page per paper see prototype http://ceur-ws.bitplan.com/index.php/Vol-2644#_9ed181c15d910b37c021a0e2fb4fdf09

[WolfgangFahl]

this would be a followup to #25 - if all metadata is in wikidata we don't need our own meta-data infrastructure any more but just provide the result files and the editing workflow.