0.0.0.0:80: bind: address already in use, errors in logs

@smusali is already working on this.

Since Jul 24, 2020.

Hi, we've having constant errors in the logs when starting this container.

```
...more
2020/07/24 16:29:22 http[logs,routes]:80 ended: listen tcp 0.0.0.0:80: bind: address already in use,
# logspout v3.2.6-custom by gliderlabs,
# adapters: logdna,
# options : persist:/mnt/routes,
# jobs : pump routes http[logs,routes]:80,
# routes :,
# ADAPTER ADDRESS CONTAINERS SOURCES OPTIONS,
# logdna map[],
2020/07/24 16:30:22 http[logs,routes]:80 ended: listen tcp 0.0.0.0:80: bind: address already in use,
# logspout v3.2.6-custom by gliderlabs,
# adapters: logdna,
# options : persist:/mnt/routes,
# jobs : http[logs,routes]:80 pump routes,
# routes :,
# ADAPTER ADDRESS CONTAINERS SOURCES OPTIONS,
# logdna map[],
2020/07/24 16:31:23 http[logs,routes]:80 ended: listen tcp 0.0.0.0:80: bind: address already in use,
...more
```

This seems to happen every minute. Here's the `docker-compose.yaml` we're using:
```
version: '3'
services:
logdna-containers:
image: logdna/logspout:latest
restart: unless-stopped
network_mode: host
hostname: logdna-containers
container_name: logdna-containers
environment:
LOGDNA_KEY: "xxxx"
TAGS: "container"
volumes:
- /etc/hostname:/etc/host_hostname:ro
- /var/run/docker.sock:/var/run/docker.sock
```

1) Can you tell us what is going on ?
2) What is the use of listening to port 80 ?

Thanks