refactor(naming): harmonize controller and route file names

- Delete product.controller.js, merge unique functions into products.controller.js
- Rename user.controller.js → users.controller.js, user.routes.js → users.routes.js
- Remove dead herowars/herowars.routes.js reference from herowars index
- Update all import paths accordingly

src/routes/api/cms/index.js

@@ -1,6 +1,6 @@
 var routes = require('express').Router();
 
-routes.use('/user', require('./user.routes'));
+routes.use('/user', require('./users.routes'));
 routes.use('/articles', require('./articles.routes'));
 routes.use('/comments', require('./comments.routes'));
 routes.use('/profiles', require('./profiles.routes'));