17 add the ability to save rdf models

[OwenR-York]

Added the ability to store data models.

• All data and schema models are loaded into a dataset, to form union models for inference
• Store writes out all the data models in the dataset to storage
• Store with a location URI treats the location as a folder, and writes data models as files (with the same name) to the new folder

Tests have been created

• Check the test environment file system, read/write access is needed for tests to work
• Loading/Storing data models to the same/new location
• Storing with a URI missing the last "/", which is corrected before storing
• Storing data models, when a URI is present but no model
• Storing data model when no URIs or models are present