jsons should not exclusively load json or args

[RussTorres]

It's counterintuitive to have to do, e.g.:

tform = Transform(json={'className': 'some.java.class', 'dataString': 'some string'})
tform.transformId = "myfavoritetransform"

when we could pretty easily have it work with

tform = Transform(json=tformdict, transformId="myfavoritetransform")

Pretty benign in the transform example, but I think this could save some lines and iteration when it comes to working with things like tilespec layout data.