Improve error handling

[jpolo]

Hi !

I have written a custom plugin for my project. It seems that when the track plugin method throws/rejects the Analytics.track method never resolve nor reject (=> in other words, my unit test times out).

Rather than forwarding rejection to the Analytics.track (We often assume that logging, sending analytics is a failsafe operation) I would suggest to implement an 'error' event that could make possible to log somewhere (console, logger, etc).

Thanks in advance !