CDK-424: Do not create .filename.crc checksums.

This uses the raw filesystem to avoid creating checksums. Checksums were
causing file reads to fail after editing schema files.

This also consolidates reading and writing to cut down on duplication.
The new BaseCommand abstract class provides helper methods to read and
create files correctly with the default FS.
CDK-424: Use single quote in schema docs.

This avoids escaped qutoes in schemas, which break Hive.
CDK-424: Add support for tab-separators in the CLI.