Add concept scheme and cleanup Turtle

[anarchivist]

• Add @musebrarian's rebased/squashed work on a SKOS concept scheme with colections.
• Improve IRI usage to make it easier to be consistent.
• Add some place holder entities for the working group itself and the concept for "educational use". (NB: I know we want to use an existing entity if possible, so we can fix this down the road.)
• Regularize whitespace throughout the Turtle file.