Various kube-prometheus fixes

Previously the script errored out, as ServiceMonitor objects are only
registered once the Prometheus Operator is running.

kube-prometheus: Move service monitors to target folder

With 1d00e0ab ("ServiceMonitor: Enable Prometheus to select ServMon
outside own ns") merged: To emphasize the fact, that ServiceMonitors can
be deployed alongside their targets, this patch moves the Alertmanager,
Kube-State-Metrics, Node-Exporter and Prometheus Operator
Service-Monitor into the respective target folder in the kube-prometheus
project.

Convert kube-prometheus to jsonnet

In kubeadm 1.10 (and perhaps earlier versions, not sure), ctrl-mgr and scheduler pods' label key is `component=` rather than `k8s-app=`, which is the selector key used for kube-prometheus exporters for these components.

Enable Thanos sidecar

In preparation of PR #1206 [1], This patch moves the Thanos manifests to the
`experimental` folder.

[1] https://github.com/coreos/prometheus-operator/pull/1206

Fixed CPU accounting in recording rules

* in description is displayed correctly namespace

* Bump kube state version

* Update Chart.yaml

Currently, node recording rules feature
an incorrect idle CPU accounting. This
change aims to fix that.

Cut 0.18.1 back to master

* charts: Add Core DNS Support

With CoreDNS becoming a first class citizen it should be an optional part
of the kube-prometheus deployment.

Fixes: #1174

* added kube-prometheus service and service monitor

In order to work directly with a cluster created by bootkube used port 9153,
and created a service exposing metrics since bootkube does does not. Also in
the helm chart changed the default port to 9153 since that is the coredns
plugins default port and to be consistent throughout the repo.

Signed-off-by: Sébastien GLON <sebastien.glon@akeneo.com>

prometheus: Add ability to whitelist Kubernetes labels

The current example-app setup in the kube-prometheus project is able to
discover scraping targets in the default namespace. It is not able to
discover the configured Alertmanager in the monitoring namespace.

This patch adds an alertmanager-discovery rbac role, to permit the
above described action. In addition it does the following cleanups:

- Remove kubeconfig configuration in deploy and teardown script. kubectl
chooses .kube/config whenever KUBECONFIG is not set by default

- Remove namespace specification option via NAMESPACE env var. In most
of the manifests the metadata/namespace was hardcoded anyways, in
addition in the promtheus frontend role binding the service account
namespace is hardcoded to default as well.

- Instead of `kubectl {apply,delete}` individual manifests, the deploy
and teardown shell scripts {apply,delete} on the entire folder.

In some cases we have been using `alert-rules` in some cases
`prometheus-rulefiles`. This led to confusion [1]. Instead, unify the
Prometheus rules configmap labels to:

```yaml
labels:
  role: alert-rules
```

[1] https://github.com/coreos/prometheus-operator/issues/1102

The `prometheus-frontend` role of the example app kubeprometheus section
is scoped to the default namespace. Thereby the frontend Prometheus
instance is not able to discover anything outside of the default
namespace. We might as well restrict the front end service monitor to
the default namespace too.

One of the `sed` commands for updating the kubeadm systemd
file (`/etc/systemd/system/kubelet.service.d/10-kubeadm.conf`)
was missing a `-i` reference to the file itself, causing it
to hang indefinitely if ran as declared.

I also wrapped this second `sed` in an `if grep ...` check,
in order to make the operation idempotent.