Updated Json behaviour so it doesn't stringify everything. For context:

https://groups.google.com/forum/#!topic/cascading-user/BqaQ5SOoZ3E/discussion

I tried json4s, parsing.json.JSONObject and spray-json before going back to Jerkson:

* json4s and spray-json didn't seem to support JSONifying a Map[String, AnyRef] out of the box. Weird
* Jerkson and parsing.json.JSONObject unfortunately convert a Scala value of 42 to 42.0 in JSON. Not sure why. I have neatly sidestepped this in my updated test

Anyway, I think this implementation is still better than what went before! Hope the Etsy crew don't mind it.
Added tip to run only one test
Add GeneratedTupleAdders to TDsl.
Merge pull request #284 from azymnis/tdsl_add_tuple_adders

Add GeneratedTupleAdders to TDsl.
Merge pull request #283 from snowplow/develop

Updated Json behaviour so it doesn't stringify everything