Use ValuePipe for Scalar2
cleanups + Either methods to the Typed-API
Merge pull request #628 from twitter/fix-scalar2

Use ValuePipe for Scalar2
Remove unneeded type parameter
Fix overrides
Fix comments, add some spaces
Merge branch 'develop' into either

Conflicts:
	scalding-core/src/main/scala/com/twitter/scalding/typed/ValuePipe.scala
Handle merges
Merge pull request #633 from twitter/either

cleanups + Either methods to the Typed-API