Add missing Spec overloads.
Add missing Spec overloads.

cloudRoutine/FsCheck,ploeh/FsCheck,forki/FsCheck,jhamm/FsCheck,paulyoung/FsCheck,paulyoung/FsCheck,ErikSchierboom/FsCheck,forki/FsCheck,fsharp/FsCheck,cloudRoutine/FsCheck,fscheck/FsCheck,sideeffffect/FsCheck,fscheck/FsCheck