refactor(refresher): allow refresher content customization

Breaking Change:

## Refresher:

- `<ion-refresher>` now takes a child `<ion-refresher-content>`
component.
- Custom refresh content components can now be replaced for Ionic's
default refresher content.
- Properties `pullingIcon`, `pullingText` and `refreshingText` have
been moved to the `<ion-refresher-content>` component.
- `spinner` property has been renamed to `refreshingSpinner` and now
goes on the `<ion-refresher-content>` component.
- `refreshingIcon` property is no longer an input, but instead
`refreshingSpinner` should be used.

Was:

```
<ion-refresher (refresh)="doRefresh($event)"
pullingIcon="arrow-dropdown">
</ion-refresher>
```

Now:

```
<ion-refresher (refresh)="doRefresh($event)">
  <ion-refresher-content
pullingIcon="arrow-dropdown"></ion-refresher-content>
</ion-refresher>
```

ionic/components/input/input-base.ts

@@ -438,7 +438,7 @@ export class InputBase {
     if (this._useAssist && this._scrollView) {
       setTimeout(() => {
         this.deregScrollMove();
-        this._deregScroll = this._scrollView.addScrollEventListener(this._scrollMove);
+        this._deregScroll = this._scrollView.addScrollListener(this._scrollMove);
       }, 80);
     }
   }