Fixed ValueError when install on Windows

When install on Windows, it raise ValueError:

    pip install qrcode -U
    Downloading/unpacking qrcode
    Downloading qrcode-2.5.tar.gz
    Running setup.py egg_info for package qrcode
    Installing collected packages: qrcode
    Running setup.py install for qrcode
        Traceback (most recent call last):
        File "<string>", line 1, in <module>
        
        ... 
        
                dir = convert_path(f[0])
        File "C:\Python26\lib\distutils\util.py", line 201, in convert_path
            raise ValueError, "path '%s' cannot end with '/'" % pathname
        ValueError: path 'share/man/man1/' cannot end with '/'