Bioschemas updates

[cthoyt]

Completeness

There are several entries in Bioversions that don't have bioregistry pages. These should still get some information, but I need to update the output (see #13)

Conformance

"http://purl.org/dc/terms/conformsTo": {
    "@type": "CreativeWork", 
    "@id": "https://bioschemas.org/profiles/Dataset/0.4-DRAFT/"
},

If you are claiming conformance, then you will need to add some more properties:

• description (this is needed for Google dataset search)
• identifier
• keywords
• license

Originally posted by @AlasdairGray in #11 (comment)