fix: can't click on avatars when on my profile page

Meta: [Can’t click on avatars when on my own profile page](http://meta.discourse.org/t/can-t-click-on-avatars-when-on-my-own-profile-page/4977)

- [x] added a `userUrl` utility method
- [x] added a `userUrl` property on `user_action` calling the previous method
- [x] updated the template to use this property