Make clearSelection public.

src/lib/template/array-selector.html

@@ -85,7 +85,7 @@ is false, `selected` is a property representing the last selected item.  When
       multi: {
         type: Boolean,
         value: false,
-        observer: '_resetSelection'
+        observer: 'clearSelection'
       },
 
       /**
@@ -108,7 +108,12 @@ is false, `selected` is a property representing the last selected item.  When
       }
     },
 
-    _resetSelection: function() {
+    /**
+     * Clears the selection state.
+     *
+     * @method clearSelection
+     */
+    clearSelection: function() {
       // Unbind previous selection
       if (Array.isArray(this.selected)) {
         for (var i=0; i<this.selected.length; i++) {