The 'passenger_use_global_queue' directive is obsolete

On Centos, using 
```
nginx.x86_64 0.15-5.el6
```

You often see
```
2013/08/19 14:48:40 [alert] 1560#0: The 'passenger_use_global_queue' directive is obsolete and doesn't do anything anymore. Global queuing is now always enabled. Please remove this configuration directive. in /etc/nginx/conf.d/passenger.conf:5
```
in the error logs.