Treat \ as a valid path separator on windows
Treat \ as a valid path separator on windows

Otherwise it breaks on windows, and no one actually uses back slashes as
part of a filename in Unix anyway.

Re isaacs/node-glob#145

isaacs/minimatch,weebygames/minimatch,PeterDaveHello/minimatch,isaacs/minimatch,volving/minimatch,djchie/minimatch,modulexcite/minimatch-1,zwhitchcox/minimatch