CDK-453: Add Dataset#getUri.
CDK-453: Add Datasets#repositoryFor.

This adds Datasets.repositoryFor(URI) that returns the repository
responsible for a dataset URI. This makes it no longer necessary to add
the DatasetRepository URI to each DatasetDescriptor, which causes test
problems.
CDK-453: Update dataset input/output format configuration.
Add Copyright to URIBuilder.
CDK-453: Move URI construction into FS repositories.

Some tests were failing because the repository did not have a URI and
could not use it to construct dataset URIs. This moves the repo URI
building into the repository's constructor rather than just using the
builder. This ensures repositories will always have a URI that can be
parsed by URIPattern.