Fixed continous scroll

To address #623, I propose the following change. The continuous load will kick off if the pagination element is in the viewport. 

I've also fixed incorrect calls to runInPageContext. You'll need to either pass in a real function, or a string representation of a complete function. 

```javascript
runInPageContext(function() { alert('hello'); });
runInPageContext("function() { alert('world');}");
```