prometheus-to-sd --dynamic-source is resolving pods in kube-system

Hi, I have this DaemonSet :
```
apiVersion: apps/v1
kind: DaemonSet
metadata:
name: {{ template "prometheus.fullname" . }}
labels:
app: {{ template "prometheus.name" . }}
chart: {{ template "qpipeline.chart" . }}
release: {{ .Release.Name }}
heritage: {{ .Release.Service }}
spec:
selector:
matchLabels:
monitor: kamon-to-prometheus
template:
metadata:
labels:
monitor: kamon-to-prometheus
spec:
containers:
- name: prometheus-to-sd
image: {{ .Values.stackdriver.image }}
command: ["/monitor", "--stackdriver-prefix={{ .Values.stackdriver.prefix }}",
"--dynamic-source=mix:http://:{{ .Values.stackdriver.port }}{{ .Values.stackdriver.endpoint }}?podIdLabel=kamon-to-prometheus&namespaceIdLabel=default",
"--namespace-id=default"]
```

To run in `default` namespace and it should resolve pods also in `default` namespace, but I cannot force it and I get :
```
main.go:123] pods is forbidden: User "system:serviceaccount:default:default" cannot list pods in the namespace "kube-system": Unknown user "system:serviceaccount:default:default"
```
which means it tries to do service discovery in the `kube-system` instead of `default` ... It is hardcoded here for `kube-system` https://github.com/GoogleCloudPlatform/k8s-stackdriver/blob/edcfb0bfdb9b25422ed235615b39a4c024d9de09/prometheus-to-sd/config/dynamic_source.go#L17

I mean, I'm running this DaemonSet in `default` namespace and all pods that it should discover lives also in `default` namespace, but it has hardcoded `kube-system` namespace. Shouldn't it use the `--namespace-id` flag instead of it being a constant?