Fixed and improved StackOverflow integration

Since the StackOverflow 1.x API was shutdown on May 12th 2014 (https://api.stackexchange.com/docs/api-v1-shutdown), here is the new implementation using the new StackExchange 2.2 API. As a improvement, now each timeline item is linked to its own URL instead of the activity tab.

You can see the result here: http://jihonrado.es