Added instances for NonEmptyList and accompanying spec.
Arbitrary[OneAnd[List,A]] used to derive Arbitrary[NonEmptyList[A]]
Added iso from NonEmptyList to AndOne[List]
index refactored to use Head and Tail
Added Cons and Snoc instances for NonEmpytList
Added tests for head,tail,cons and snoc
Fix bug in nelFieldOne, replace the head - not append
Merge branch 'master' into nonemptylist
Updated to use cons1 and snoc1.
removed snoc and cons instances
removed cons/snoc tests for nonemptylist
using nel over apply
Merge pull request #149 from MaxWorgan/nonemptylist

Added instances for NonEmptyList and accompanying spec.