Change milliseconds to hours min sec ms format.

def _msToString(self, ms):
        """Change milliseconds to hours min sec ms format."""
        hr, ms = divmod(ms, 3600000)
        mins, ms = divmod(ms, 60000)
        secs, mill = divmod(ms, 1000)
        return "%ihr %imin %isecs %ims" % (hr, mins, secs, mill)