feat($ionicScrollDelegate): expose zoomBy and zoomTo methods

Closes #1977

Author: ajoslin

js/angular/controller/scrollController.js

@@ -140,6 +140,18 @@ function($scope, scrollViewOptions, $timeout, $window, $$scrollValueCache, $loca
     });
   };
 
+  this.zoomTo = function(zoom, shouldAnimate, originLeft, originTop) {
+    this.resize().then(function() {
+      scrollView.zoomTo(zoom, !!shouldAnimate, originLeft, originTop);
+    });
+  };
+
+  this.zoomBy = function(zoom, shouldAnimate, originLeft, originTop) {
+    this.resize().then(function() {
+      scrollView.zoomBy(zoom, !!shouldAnimate, originLeft, originTop);
+    });
+  };
+
   this.scrollBy = function(left, top, shouldAnimate) {
     this.resize().then(function() {
       scrollView.scrollBy(left, top, !!shouldAnimate);

js/angular/service/scrollDelegate.js

@@ -93,6 +93,24 @@ IonicModule
    * @param {boolean=} shouldAnimate Whether the scroll should animate.
    */
   'scrollBy',
+  /**
+   * @ngdoc method
+   * @name $ionicScrollDelegate#zoomTo
+   * @param {number} level Level to zoom to.
+   * @param {boolean=} animate Whether to animate the zoom.
+   * @param {number=} originLeft Zoom in at given left coordinate.
+   * @param {number=} originTop Zoom in at given top coordinate.
+   */
+  'zoomTo',
+  /**
+   * @ngdoc method
+   * @name $ionicScrollDelegate#zoomBy
+   * @param {number} factor The factor to zoom by.
+   * @param {boolean=} animate Whether to animate the zoom.
+   * @param {number=} originLeft Zoom in at given left coordinate.
+   * @param {number=} originTop Zoom in at given top coordinate.
+   */
+  'zoomBy',
   /**
    * @ngdoc method
    * @name $ionicScrollDelegate#getScrollPosition