[FIX] web: avoid memory leak

Methods are bound on button but never release.

addons/web/static/src/js/views/form/form_controller.js

@@ -33,6 +33,15 @@ var FormController = BasicController.extend({
         this.toolbar = params.toolbar;
         this.mode = params.mode;
     },
+    /**
+     * @override
+     */
+    destroy: function () {
+        if (this.$buttons) {
+            this.$buttons.find('*').off();
+        }
+        this._super();
+    },
 
     //--------------------------------------------------------------------------
     // Public

addons/web/static/src/js/views/kanban/kanban_controller.js

@@ -43,6 +43,11 @@ var KanbanController = BasicController.extend({
         // true iff grouped by an m2o field and group_create action enabled
         this.create_column_enabled = false;
     },
+    destroy: function () {
+        if (this.$buttons) {
+            this.$buttons.off();
+        }
+    },
 
     //--------------------------------------------------------------------------
     // Public

addons/web/static/src/js/views/list/list_controller.js

@@ -42,6 +42,12 @@ var ListController = BasicController.extend({
         this.noLeaf = params.noLeaf;
         this.selectedRecords = []; // there is no selected record by default
     },
+    destroy: function () {
+        if (this.$buttons) {
+            this.$buttons.find('*').off();
+        }
+        this._super();
+    },
 
     //--------------------------------------------------------------------------
     // Public