1. in capistrano 3.1, `after` and `before` will immediately looking for the given task(see commit capistrano/capistrano@a58bb3b). That makes the `after` hook must be invoke after the task declared
2. make 4 lines to 1 line
3. After capistrano 3.1, you can write `after 'deploy:finished', :smart_restart` here(without current namespace __'puma'__). But for the backward compatible, still use full name here