Adds a new widget for the Errbit server

* Show the unresolved errors for an unlimited number of Errbit projects
* Specify the Errbit server in `ERRBIT_URL`
* Specify the API keys for every relevant Errbit project in `ERRBIT_KEYS` (separated by comma)

![neo 2013-12-06 19-45-19](https://f.cloud.github.com/assets/678542/1694731/a75bb6ac-5ea6-11e3-9e3c-bc4a8da9c825.png)
![neo 2013-12-06 19-45-51](https://f.cloud.github.com/assets/678542/1694732/a92c1eae-5ea6-11e3-8f77-6e465d6d0fbb.png)