release interact instance,and repaire the grid layout self spell mistask

Author: guoyangyang

src/GridItem.vue

@@ -285,6 +285,7 @@
             this.eventBus.$off('setRowHeight', self.setRowHeightHandler);
             this.eventBus.$off('directionchange', self.directionchangeHandler);
             this.eventBus.$off('setColNum', self.setColNum);
+            this.interactObj.unset() // destroy interact intance
         },
         mounted: function () {
             this.cols = this.$parent.colNum;

src/GridLayout.vue

@@ -117,9 +117,9 @@
         },
         beforeDestroy: function(){
             //Remove listeners
-            this.eventBus.$off('resizeEvent', self.resizeEventHandler);
-            this.eventBus.$off('dragEvent', self.dragEventHandler);
-            window.removeEventListener("resize", self.onWindowResize)
+            this.eventBus.$off('resizeEvent', this.resizeEventHandler);
+            this.eventBus.$off('dragEvent', this.dragEventHandler);
+            window.removeEventListener("resize", this.onWindowResize)
         },
         mounted: function() {
             this.$nextTick(function () {