Rollbar.com support + tests

I've set it up to use a test account on rollbar.com which will get log messages each time the test is run, (as part of the test.)

If you'd like access, email me at cory@rollbar.com and I'll add you to the project.

By default, window.onerror() is hooked and all track() calls will send an INFO message to rollbar.com. The track option can be disabled via:

```javascript
analytics.initialize({
  "Rollbar": {
    accessToken: "XXXXXXXXXX",
    track: false
  }
});
```