Add parameter for host to bind

Currently the host is hardcoded, would be good to have a parameter for it.

```go
addr := net.JoinHostPort("0.0.0.0", strconv.Itoa(int(config.GetPort())))
````

Maybe you want to serve localhost only.

```
   --host string         The host to serve on (default: "0.0.0.0")
```