Support bytes

```
def hashi(self, key, replica=0):
        """Returns a ketama compatible hash from the given key."""
        dh = self._listbytes(md5(str(key).encode("utf-8")).digest())
        ...
```

`hashi(b'abc')` returns in `dh=md5(b"b'abc'")` instead of `dh=md5(b'abc')`.