Turtle should be compatible with tyto

[bbartley]

Currently, all classes in paml.ttl and uml.ttl lack rdfs:labels which means they are not accessible to URI lookup via tyto.

[rpgoldman]

@bbartley Should we extend the tests so that we verify that classes have labels?

If so, should we have some way to mark a class as not needing a label, or should we just be uniform, whether a class is going to end up on tyto or not?

I'm inclined to think the latter to avoid confusion, but am open to other choices.

Also, do we need to label properties as well?

[bbartley]

This is somewhat of a non-answer, but practically speaking, we only need labels on a few of the classes, e.g., SampleArray, SampleMask, ValueSpecification, SampleData etc., that are likely to be used as inputs and outputs for a Primitive... the idea being that users don't have to remember the URIs when they define a Primitive or Protocol inputs and outputs, they can just use tyto.PAML.SampleData for example.