fix(ionCheckbox): make ng-checked and ng-change work

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>
```

js/angular/directive/checkbox.js

@@ -21,30 +21,30 @@ IonicModule
     restrict: 'E',
     replace: true,
     require: '?ngModel',
-    scope: {
-      ngModel: '=?',
-      ngValue: '=?',
-      ngChecked: '=?',
-      ngDisabled: '=?',
-      ngChange: '&'
-    },
     transclude: true,
-
     template: '<label class="item item-checkbox">' +
                 '<div class="checkbox checkbox-input-hidden disable-pointer-events">' +
-                  '<input type="checkbox" ng-model="ngModel" ng-value="ngValue" ng-change="ngChange()">' +
+                  '<input type="checkbox">' +
                   '<i class="checkbox-icon"></i>' +
                 '</div>' +
                 '<div class="item-content disable-pointer-events" ng-transclude></div>' +
               '</label>',
-
     compile: function(element, attr) {
       var input = element.find('input');
-      if(attr.name) input.attr('name', attr.name);
-      if(attr.ngChecked) input.attr('ng-checked', attr.ngChecked);
-      if(attr.ngDisabled) input.attr('ng-disabled', attr.ngDisabled);
-      if(attr.ngTrueValue) input.attr('ng-true-value', attr.ngTrueValue);
-      if(attr.ngFalseValue) input.attr('ng-false-value', attr.ngFalseValue);
+      forEach({
+        'name': attr.name,
+        'ng-value': attr.ngValue,
+        'ng-model': attr.ngModel,
+        'ng-checked': attr.ngChecked,
+        'ng-disabled': attr.ngDisabled,
+        'ng-true-value': attr.ngTrueValue,
+        'ng-false-value': attr.ngFalseValue,
+        'ng-change': attr.ngChange
+      }, function(value, name) {
+        if (isDefined(value)) {
+          input.attr(name, value);
+        }
+      });
     }
 
   };

test/html/toggle.html

@@ -17,6 +17,12 @@ <h1 class="title">Toggle</h1>
       <div ng-controller="TestCtrl">
 
         <div class="list">
+          <ion-checkbox ng-model="checkModel" ng-change="myChange = checkModel">
+            Main Check
+          </ion-checkbox>
+          <ion-checkbox ng-checked="myChange">
+            Follows ng-change of Main Check
+          </ion-checkbox>
           <ion-toggle ng-model="myModel" ng-disabled="isDisabled">myModel ({{!!myModel}})</ion-toggle>
           <ion-toggle ng-model="catModel" ng-disabled="isDisabled" ng-true-value="cats" ng-false-value="dogs">Cats or dogs? ({{catModel}})</ion-toggle>
           <ion-toggle ng-model="isDisabled">Disable myModel ({{!!isDisabled}})</ion-toggle>

test/unit/angular/directive/checkbox.unit.js

@@ -28,13 +28,28 @@ describe('Ionic Checkbox', function() {
   });
 
   it('should pass down attrs', function() {
-    el = compile('<ion-checkbox ng-checked=1 ng-disabled=2 ng-true-value=3 ng-false-value=4>')(scope);
+    el = compile('<ion-checkbox name="name" ng-model="model" ng-checked="checked" ng-disabled="disabled" ng-true-value="true-value" ng-false-value="false-value" ng-change="change">')(scope);
     scope.$apply();
     var input = el.find('input');
-    expect(input.attr('ng-checked')).toBe('1');
-    expect(input.attr('ng-disabled')).toBe('2');
-    expect(input.attr('ng-true-value')).toBe('3');
-    expect(input.attr('ng-false-value')).toBe('4');
+    expect(input.attr('name')).toBe('name');
+    expect(input.attr('ng-model')).toBe('model');
+    expect(input.attr('ng-checked')).toBe('checked');
+    expect(input.attr('ng-disabled')).toBe('disabled');
+    expect(input.attr('ng-true-value')).toBe('true-value');
+    expect(input.attr('ng-false-value')).toBe('false-value');
+    expect(input.attr('ng-change')).toBe('change');
+  });
+
+  it('shouhld ngChecked properly', function() {
+    el = compile('<ion-checkbox ng-checked="shouldCheck">')(scope);
+    scope.$apply();
+    var input = el.find('input');
+    expect(input[0].hasAttribute('checked')).toBe(false);
+    scope.$apply('shouldCheck = true');
+    expect(input[0].hasAttribute('checked')).toBe(true);
+    scope.$apply('shouldCheck = false');
+    expect(input[0].hasAttribute('checked')).toBe(false);
+
   });
 
 });