Bumped version to RC6.
Bumped version to RC6.

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