Add support for sending code snippets with stacktrace

Add support for sending code snippets with stacktrace, for display on Bugsnag dashboard

![screenshot 2014-12-15 18 13 00](https://cloud.githubusercontent.com/assets/104009/5448360/262f12d6-8493-11e4-83b7-c8bd2c303f95.png)

Fixed, thanks!