adding install.ps1 for nunit package, WIP
adding install.ps1 for nunit package, WIP

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