title: ng-model inside $ionicPopup templateUrl is not working with scope
body: <p>This is my controller code. Show a popup and on button click, make some validations:</p>
  
  <pre><code>UZCampusWebMapApp.controller('PlanCtrl',function($scope, $ionicModal, $ionicLoading, $ionicPopup) {
  
      $scope.confirmCreatePOI = function(data) {
          var myPopup = $ionicPopup.show({
              templateUrl: 'templates/pois/confirmCreatePOI.html',
              title: 'Confirmar creación de POI',
              scope: $scope,
              buttons: [
                  {
                      text: '&lt;b&gt;Save&lt;/b&gt;',
                      onTap: function() {
                          var invalidEmail = $scope.email.length==0 || $scope.email==null || typeof($scope.email)=='undefined';
                          if ($scope.emailChecked==true &amp;&amp; invalidEmail) {
                              $ionicLoading.show({ template: 'Email is mandatory'});
                          }
                          else {
                              data.email = $scope.email;
                              $scope.finalSubmitCreatePOI(data);
                          }
                      }
                  },
                  { 
                     text: 'Cancel'
                  }
              ]
          });
      };
  });
  </code></pre>
  
  <p>This is the directive code where the previous controller function <code>confirmCreatePOI</code> is called:</p>
  
  <pre><code>    UZCampusWebMapApp.directive('formCreatePointOfInterest', function($ionicLoading) {
        return {
          restrict : 'A',
          scope: true,
          controller : function($scope) {      
            $scope.submit = function(data) {
              console.log("Submit form createpoint of interest",data);
              if($scope.createPOIform.$valid) {
                $scope.confirmCreatePOI($scope.data);
              } else {
                $ionicLoading.show({ template: 'El formulario es inválido', duration: 1500})
              }
            }
          }
        }
      });
  </code></pre>
  
  <p>And this is my templateUrl code:</p>
  
  <pre><code>&lt;div id="confirm-create-poi-popup"&gt;
    &lt;p&gt; Text &lt;/p&gt;
    &lt;p&gt; Text &lt;/p&gt;
    &lt;div class="list"&gt;
      &lt;ion-checkbox ng-model="emailChecked"&gt;Receive notification&lt;/ion-checkbox&gt;
      &lt;label class="item item-input"&gt;
        &lt;input type="email" ng-model="email"&gt;
      &lt;/label&gt;
    &lt;/div&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>So, after user have clicked on <em>'Save'</em> button ( <em>onTap</em> event), I would like to check if email has been entered on input field.</p>
  
  <p>But when I check it with the comprobation:</p>
  
  <pre><code>var invalidEmail = $scope.email.length==0 || $scope.email==null || typeof($scope.email)=='undefined';
  </code></pre>
  
  <p>The <code>$scope.email.length==0</code> expression returns an error because email is undefined, so <code>ng-model</code> property isn't working with the <code>$scope</code>, I'm not getting any value on <code>$scope.email</code></p>
  
  <p>Why is that? Is the <code>$ionicPopup $scope</code> property not working? Wrongly used?</p>