Stale apple connections

I am under the impression that the connection to apple should only be used for 10 minutes. e.g.: https://github.com/neoziro/node-apns

I'm not sure if we should be tracking inactivity, or the duration of the connection in general. I chose the latter.

- keep the ssl connection object around (though the connection inside is closed) - no real reason to remove
- add some method delegation - taking the lead from the connection class
- add a connection_timeout parameter and the concept of a stale connection. Meaning, one that we opened a while ago.

If you want me to split into multiple pull requests, let me know

--Keenan