Fixes#1073
ion-infinite-scroll will now fire a scroll event if the user scrolls
past the left boundaries (if they exist) or the top boundaries (if they
exists). This means infinite scroll works for vertical, horizontal, or
vertical plus horizontal scrolling situations.
Closes#760
BREAKING CHANGE: on-refresh and on-refresh-opening are no longer on the
ion-content directive. They are on the ion-refresher. In addition,
on-refresh-opening has been renamed to on-pulling.
Change your code from this:
```html
<ion-content on-refresh="onRefresh()"
on-refresh-opening="onRefreshOpening()">
<ion-refresher></ion-refresher>
</ion-content>
```
To this:
```html
<ion-content>
<ion-refresher on-refresh="onRefresh()"
on-pulling="onRefreshOpening()">
</ion-refresher>
</ion-content>
```
