Show streams on circuits

Arm should show the targets of individual streams. For example, currently arm might show a new stream like this (spaces removed):

127.0.0.1:42051 --> 127.0.0.1:9050 UNKNOWN 0.0s (SOCKS)    

Of course the destination is 127.0.0.1:9050. That's just our socksport, and it provides no new information to the arm user. The destination should be shown as the target of the stream.

Once the stream is attached to a circuit, this binding should be shown explicitly. Note that this is not entirely trivial to do: for example, sometimes streams are reattached to different circuits (e.g. if a particular circuit does not work).

It might also be useful to indicate the status of a particular stream, e.g. "SENTRESOLVE", "SUCCEEDED", etc.