fix(toggle): fix ngChange being reported before model changes

Closes #1349, #1741

BREAKING CHANGE:

ion-toggle no longer has an isolate scope.
This will break your toggle only if you were relying upon the toggle
having an isolate scope: if you were referencing `$parent.value` as
the ng-disabled attribute, for example.

Change your code from this:

<ion-toggle ng-disabled="{{$parent.isDisabled}}"></ion-toggle>

To this:

<ion-toggle ng-disabled="{{isDisabled}}"></ion-toggle>

test/html/toggle.html

@@ -18,6 +18,9 @@
       <div ng-controller="TestCtrl">
 
         <div class="list">
+          <ion-toggle ng-model="checkModel2" ng-change="myChange = checkModel2">
+            Main Check
+          </ion-toggle>
           <ion-checkbox ng-model="checkModel" ng-change="myChange = checkModel">
             Main Check
           </ion-checkbox>