Clean up JSON Reader code, move it to Low-Level Framework.

[robmccrady]

I needed code to read through a JSON string coming back from API Responses. Rather than create concrete classes to deserialize into, I created some code that can drill through the JSON Document to find a value at a Path.

This code is messy, and could be used in several other uses, so let's make it good, and move it to the iFX project.