Closes#1349. Closes#1361
BREAKING CHANGE: ion-checkbox no longer has an isolate scope.
This will break your checkbox only if you were relying upon the
checkbox having an isolate scope: if you were referencing
`$parent.value` as the ng-disabled attribute, for example.
Change your code from this:
```html
<ion-checkbox ng-disabled="{{$parent.isDisabled}}"></ion-checkbox>
```
To this:
```html
<ion-checkbox ng-disabled="{{isDisabled}}"></ion-checkbox>
```
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