gristle_validator - make mature

[kenfar]

The gristle_validator should be enhanced to make it a mature utility. This would include:

• the ability to show validation stats only - without output data (which could be voluminous and slow down processing)
• the ability to detect inconsistent quoting.
• the ability to detect incorrect field types - based on a configuration file listing of field types (or eventually a connection to the metadata database or a target database and table)
• the ability to detect incorrect values (comparing to min, max, string length, null value, or invalid date) - again based on a config file or metadata
• and a great test harness