Closes#1741
BREAKING CHANGE:
ion-radio no longer has an isolate scope.
This will break your radio only if you were relying upon the radio having an isolate scope: if you were referencing `$parent.value` as
the ng-disabled attribute, for example.
Change your code from this:
<ion-radio ng-disabled="{{$parent.isDisabled}}"></ion-radio>
To this:
<ion-radio ng-disabled="{{isDisabled}}"></ion-radio>
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