feat($ionicSlideBoxDelegate): add start() to resume after stop

Closes #1584

js/angular/service/slideBoxDelegate.js

@@ -77,6 +77,12 @@ IonicModule
    * explicitly told to do so.
    */
   'stop',
+  /**
+   * @ngdoc method
+   * @name $ionicSlideBoxDelegate#start
+   * @description Start sliding again if the slideBox was stopped. 
+   */
+  'start',
   /**
    * @ngdoc method
    * @name $ionicSlideBoxDelegate#currentIndex

js/views/sliderView.js

@@ -506,6 +506,10 @@ ionic.views.Slider = ionic.views.View.inherit({
       stop();
     };
 
+    this.start = function() {
+      begin();
+    };
+
     this.currentIndex = function() {
       // return current index position
       return index;