Added init & last to Coproduct
Merge pull request #178 from stacycurl/coproduct-last-n-init

Added init & last to Coproduct
moved UnpackN instances to boilerplate, we can now count beyond two.  Also removed some duplication from Boilerplate.scala
Merge pull request #181 from kevinwright/unpack-boilerplate

moved UnpackN instances to boilerplate, fixes #107