mostly functional at this point

= ended up just using the tree/ node api a lot to simulate the
kind of parsing CodecConfig et al did. The API support for doing
global defaults, required fields, et al just isn't really there
otherwise. Wasn't worth the myriad combinations of hacks and huge
time loss.

- couple known issues: enums need to be case insensitive, _rename
directives need to be respected, 'nested primaries' need to be
ported. The dropwizard size parsing i'm using is somewhat less
generous, so might need to rethink shimming back into typesafe.