CDK-602: Rename hcatalog package to spi.hive.

With DatasetRepository removed from the public API, the HCatalog classes
can be moved to the SPI (like the FS implementation) and renamed from
HCatalog to Hive.

Also fixes uses of DatasetRepositoryException.
CDK-602: Remove Constraints Serializable methods.

Constraints are now passed in the MR formats using view URIs rather than
serializing the Constraints directly.