Redmine Integration

https://github.com/bugsnag/bugsnag-notification-plugins/issues/36

My tests are available at [here](http://red.manage.net.nz/projects/example-project/issues).

![Screenshot](http://cl.ly/image/3w1d1k3x290Z/Image%202014-07-13%20at%203.39.14%20pm.png)