Fix UnionFile.Readdir return when c <= 0

Update Readdir to match behavior of stdlib os package.

Fixes spf13#197

Fix missing bounds checking in UnionFile.Readdir

It will now return io.EOF at the end of the directory view.

Fixes spf13#194

Return nil in CopyOnWriteFs.MkdirAll when directory exists

Fixes spf13#191

Release

Release

Release

Release v1.0.2

Release v1.0.1

Release v1.0.0