Macro generated case class Tuple Setter and Converter

This is a first stab at using macros to begin generating useful code for our users.

Caveats:
* this only works on 2.10. I play around with it by doing: ```./sbt ++2.10.4 "scalding-macro/console"```
* this depends on macro paradise. I do this for quasiquotes, which GREATLY simplify the implementation... it isn't strictly necessary, but would greatly complicate things. quasiquotes are part of scala 2.11 so depending on macro paradise only for them seems ok to me.
* I need to add tests, though I've tested it along the way of course.

What are other things we might want to use macros for?
So on closer inspection of this, I'm a bit concerned that even if we could get the TypeTag's in place the case class code isn't thread safe(reflection in scala isn't), which would just be a little odd. But also if you don't use the macro tuple setters/getters that must align to these (say you make your own that does something different, re-orders or what have you), then its all wrong?