Readyevent

Is ready event not working with the latest backstopjs version on chromy ?

Here is my backstop.json file:

[backstop.json.txt](https://github.com/garris/BackstopJS/files/1254518/backstop.json.txt)

```
{
"id": "test",
"viewports": [
{
"label": "phone",
"width": 320,
"height": 480
}
],
"scenarios": [
{
"label": "Demo Page",
"url": "https://demos.artbees.net/jupiter5/?testing=1",
"hideSelectors": [],
"removeSelectors": [],
"selectorExpansion": true,
"selectors": [],
"readyEvent": "ready for rock",
"delay": 1000,
"misMatchThreshold" : 0.1,
"requireSameDimensions" : true,
"onBeforeScript": "onBefore.js",
"onReadyScript": "onReady.js"
}
],
"paths": {
"bitmaps_reference": "backstop_data/bitmaps_reference",
"bitmaps_test": "backstop_data/bitmaps_test",
"engine_scripts": "backstop_data/engine_scripts",
"html_report": "backstop_data/html_report",
"ci_report": "backstop_data/ci_report"
},
"engineFlags": [],
"engine": "chrome",
"report": ["browser"],
"debug": false,
"debugWindow": false
}
```

And this is what I get from console: