Add permissions to list and watch ConfigMaps and Secrets

[pdecat]

Required since #379

Without that, the following errors are triggered:

E  k8s.io/kube-state-metrics/collectors/collectors.go:62: Failed to list *v1.Secret: secrets is forbidden: User "system:serviceaccount:monitoring:kube-state-metrics" cannot list secrets at the cluster scope: Unknown user "system:serviceaccount:monitoring:kube-state-metrics" 
E  k8s.io/kube-state-metrics/collectors/collectors.go:62: Failed to list *v1.ConfigMap: configmaps is forbidden: User "system:serviceaccount:monitoring:kube-state-metrics" cannot list configmaps at the cluster scope: Unknown user "system:serviceaccount:monitoring:kube-state-metrics" 

Note: here, kube-state-metrics is deployed in a custom monitoring namespace.

[k8s-ci-robot]

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[pdecat]

Similar update will be needed on the helm chart: https://github.com/kubernetes/charts/blob/master/stable/kube-state-metrics/templates/clusterrole.yaml

[brancz]

lgtm 👍 thanks a lot!

[andyxning]

@pdecat Good catch. Thanks for helping us correct this. 👍