Fixed network configuration for port forwarding.

On my Mac OS X 10.8.4, following the instructions
```config.vm.network :forwarded_port, host: 4567, guest: 80```

generates the error "The network type 'forwarded_port' is not valid.
Please use 'hostonly' or 'bridged'."

looking to Vagrantfile I realized that this config was changed to
```config.vm.forward_port 80, 4567``