ontology RDF links are broken

[Vladimir Alexiev]

All links provided to download the ontology are broken:

• in http://pav-ontology.github.io/pav/:
  http://pav-ontology.github.io/pav/pav.rdf.xml, http://eelst.cs.unibo.it/apps/LODE/source?url=http://purl.org/pav/2.3
• in https://github.com/pav-ontology/pav:
  http://pav-ontology.github.io/pav/pav.rdf

A working download link is https://github.com/pav-ontology/pav/raw/gh-pages/pav.rdf.

Also, https://github.com/pav-ontology/pav says

Current version: http://purl.org/pav/ should redirect to pav.rdf from this repository.

but it doesn't

@stain posting this separately since it's more urgent than #4 and #5