Unhandled exception when connection times out

Nobody has claimed this yet.

I noticed that an unhandled exception is raised when a connection to an APN is started (to send notifications to apple devices) but the connection times out. The following error is raised:

```
throw e;
^
Error: Connect timed out
at Connection. (/home/flavio/.meteor/packages/raix_push/.3.0.2.1ojwzxu++os+web.browser+web.cordova/npm/node_modules/apn/lib/connection.js:193:36)
at Timer.listOnTimeout [as ontimeout] (timers.js:121:15)
```

and then the whole application crashes.

A quick way to reproduce this is to drop all tcp connections to outbound port 2195 via iptables on the test machine and then trying to send a notification to an apple device.

As a workaround i found that adding an event listener for the `error` event correctly fixes the problem. I'm talking about adding [here](https://github.com/raix/push/blob/8f54dbfae705584a621defc91e1c8dbf9f9a41b1/lib/server/push.api.js#L126) the following code:

```
apnConnection.on('error', function (err) {
console.log('got error: ', err);
// maybe some cleanup code here?
});
```

just like it is done for the `transmissionError` two lines below in the very same file.

What do you think?

Inspect lib/server/push.api.js around line 126 and compare the existing transmissionError handling nearby. Reproduce the timeout by blocking outbound port 2195 with iptables, then verify that sending a notification no longer crashes the application when the APN connection times out.

Written by the indexing model from the issue text.