it is confusing when unconsumed responses hang further requests to a server. rather than having agent wait quietly and patiently for the user to "do the right thing" (i.e. call `res.resume()`) let the user continue to swallow up sockets until (presumably) the net/CC3K logic throws and error, presumably fixes #674
set agent initial  maxSockets to 1 per rationale/discussion https://github.com/tessel/runtime/issues/674#issuecomment-66214631 and following
Merge #680 r=@tcr: Set default Agent's initial maxSockets to 1

The [new rationale](https://github.com/tessel/runtime/issues/674#issuecomment-66214631) here is that:

- the lower, the better as far as current CC3K stack goes
- this may also make it a little clearer where the problem lies in situations like #674, than the previous value of 2

@LinusU how does this sound as a replacement for #675?