client _handleResponse: allow string form of peer.ip

[BEP-3](http://bittorrent.org/beps/bep_0003.html) states:
> peers maps to a list of dictionaries corresponding to peers, each of which contains the keys peer id, ip, and port, which map to the peer's self-selected ID, **IP address or dns name as a string**, and port number, respectively.

The [Theory.org Wiki](https://wiki.theory.org/BitTorrentSpecification#Tracker_Response) agrees.

Is there any evidence of binary ip fields in the wild? Anyway, this code should support both.
Wow, this was not doing what it was supposed to. This code is written to handle the case where the server sends back a compact response, pulling out each individual byte (like compact2string does). We just need the ip.toString() part only.