Added 'fastMode' to aggressively empty the notification buffer

Enabling this option may not be advisable if node-apn runs within a larger application in-case it stalls while emptying a large buffer. In the case of high throughput it would be sensible to run node-apn within a separate worker process servicing a queue in which case the `fastMode` should be enabled.
Enabled the Nagle Algorithm.
Attach socket event handlers in a more sensible way.

Using `#bind()` as it was intended
Tidied up some dead code and renamed `dontServiceBuffer` to `delayServiceBuffer`
Updated feedback.js for q v0.9.x