Fix Builder naming in NUnit package.
Fix Builder naming in NUnit package.

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