Address feedback

packages/0x.js/src/utils/class_utils.ts

@@ -1,7 +1,7 @@
 import * as _ from 'lodash';
 
 export const classUtils = {
-    // This is usefull for classes that have nested methods. Nested methods don't get binded out of the box.
+    // This is useful for classes that have nested methods. Nested methods don't get bound out of the box.
     bindAll(self: any, exclude: string[] = ['contructor'], thisArg?: any): void {
         for (const key of Object.getOwnPropertyNames(self)) {
             const val = self[key];