Add support for JSON in dbRow3
Can only use like on json if cast to text first, so just remove support for filtering on it
Provide a nice error when there is malformed JSON

This will allow users to wrap their load function and use the detail to
handle bad JSON if they want to. Otherwise they can just let it error.
Dry up the JSON no supported for filtering error
Fix c/p error and scope some vars to args
Trim things that are to become JSON
Merge pull request #3 from singlebrook/json_support

Add support for JSON in dbRow3