Work where process.getuid and getgid are absent
On Windows, add base directories like \\?\c:\

The path._makeLong function will return paths like these on Windows:

    \\?\c:\foo\bar

The fs.realpath function walks through Windows paths treating '\\?\c:\' as the base directory, so this is what we store.  The process.cwd and os.tmpdir functions may not return the same case for base directory names, so we normalize to lowercase.
Instead of storing the trailing slash, ignore it
Test that process.cwd() and os.tmpdir() are created
Add note about OS and versions
Merge pull request #3 from tschaub/win

Confirm that tests pass on Windows.