Added RecordArgs support for empty argument lists.
Added RecordArgs support for empty argument lists.

fthomas/shapeless,liff/shapeless,khronnuz/shapeless,Atry/shapeless,joescii/shapeless,alexarchambault/shapeless,triggerNZ/shapeless,TomasMikula/shapeless,notxcain/shapeless,tek/shapeless,lambdista/shapeless,wheaties/shapeless,lukasz-golebiewski/shapeless,isaka/shapeless,milessabin/shapeless,roberth/shapeless,malcolmgreaves/shapeless,clhodapp/shapeless