CDK-139: Adding changable providers to repo tests.

Adding test of FS provider and FS repo. This is in preparation for
testing the FS repo with the Hive external provider.

Caught and fixed problems:
* When validating the DatasetDescriptor, equals was not implemented
* FS repo delete should return true if the provider delete returns true
CDK-139: Ported Hive integration code for locations.

Changed quite a bit... should describe here.

The new MetadataProviders are working and passing tests with FS
repositories (HCatalog's repo is based on FS).

Still need to add round-trip tests, but those should be built for all of
the dataset repositories. Removing the old tests.