Issue with GGC connection following the tutorial

Hi,

While following the tutorial of greengrass https://docs.aws.amazon.com/greengrass/v1/developerguide/module5.html I hit some connection exception.

My setup was:
* Greengrass core on a raspberry
* lightController IoT device in a docker container
* trafficLight IoT device in another docker container

The problem is that with auto detection of the core connection, my core registers
```
127.0.0.1
Port 8883
192.168.2.2
Port 8883
::1
Port 8883
```

This means that in the lightController and trafficLight code, they try to connect to the core on 127.0.0.1 which does not work.

All the core addresses should be tried until one works.