RDF'ed serialization


- added new RDF format with IS_IN_FORMAT relation
- added separate RDFS_LABEL to the RDF format
- pointed object HAS_SERIALIZATION to RDF format
- added getSerializationTitle to bridge HAS_SERIALIZATION -> IS_IN_FORMAT -> RDFS_LABEL gap
- modified unit test
- updated views page

Resolves https://www.pivotaltracker.com/story/show/65221404
That was due to the homepage ending up with a blank "Export" box, so I needed a default.

I discovered that the homepage is of nodeType mode:root and is not having Giulia's format relationship added to it. I have added those relationships.

I am still using getObjectTitle, but I have removed your hack as it is no longer necessary.