CDK-469: Move HDFS URL handler to SPI, make Configurable.

The URL handler was calling new Configuration() to get a config. This
was making tests fail when a schema URI is passed to DatasetDescriptor
and the HDFS information is not configured in the environment. The
solution is to allow the CLI to set the correct Configuration that
instances will use.
CDK-469: Pass schema URI to DatasetDescriptor in create.

This updates the create command to pass Schema URIs to
DatasetDescriptor.Builder rather than opening and passing the
InputStream. This allows the builder to use the schema URI where
possible and fixes the Hive bug that affects schemas too large for the
Hive property storage, CDK-469.
Fix deprecation warning in partition-config test.