Refactor around the macro definitions into 3 files. Both converter and s...

...etter support Options
Attempting to factor that out triggers...
[warn] /Users/ioconnell/workspace/github/scalding/scalding-macros/src/main/scala/com/twitter/scalding/macros/impl/CaseClassHelpers.scala:10: abstract type pattern c.universe.MethodSymbol is unchecked since it is eliminated by erasure
[warn]       .collect { case m: c.universe.MethodSymbol if m.isCaseAccessor => m }
[warn]                                     ^
[warn] one warning found

which doesn't reall make a lot of sense to me?