Support json column types

[joyofhex]

We've been storing some json data in postgresql and when we query it always returns as a string. This small patch will convert that json data in string format into a dictionary of values.

Before this patch a JSON column would be returned like this:

    "order": "[{\"destination\": \"EMBALLAGE\", \"type\": \"PACKET\", \"amount\": 50}]",

After applying this we get the following:

    "order": [
      {
        "destination": "EMBALLAGE",
        "type": "PACKET",
        "amount": 50
      }
    ],

I used a string to represent json in the type map as there doesn't seem to be a single object or type that would be usable as a conversion function.

Thanks for taking the time to look at this.

[kislyuk]

Thank you! Sorry about the delay. Will test and release this shortly.

[kislyuk]

This approach is incorrect and breaks downstream applications, reverting.