Triples for parent link components + Bugfix to remove links for top concepts / narrowers endpoints

[recalcitrantsupplant]

1. Add triples for the identifier and label of link parent components.
2. Bugfix to prevent creation of links for top concepts/narrowers endpoints (which were generating incorrectly - and are not necessarily required.)

Example of triples now being added for parent components in a link:

exm:TopLevelConcept a skos:Concept ;
    dcterms:identifier "exm:TopLevelConcept"^^prez:identifier ;
    prez:label "The toppiest of concepts" ;
    prez:link "/catalogs/exm:VocPrezCatalog/collections/exm:SchemingConceptScheme/items/exm:TopLevelConcept" .

exm:VocPrezCatalog dcterms:identifier "exm:VocPrezCatalog"^^prez:identifier ;
    prez:label "A Demo Catalog" .

[recalcitrantsupplant]

Will need minor changes after merging #245 and #246

[lalewis1]

looks good thanks.