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>
```