prometheus: Introduce RuleFile Custom Resource Definition 

This patch introduces a new Custom Resource Definition to the
Prometheus Operator - the Rule CRD. It addresses two main
needs:

1. Prometheus (alerting and recording) Rule validation during creation time
via Kubernetes Custom Resource Definition validation.

2. Life-cycle management of Prometheus application Rules alongside the
application itself, inside the applications Kubernetes namespace, not
necessarily the namespace of the scraping Prometheus instance.

A user defines Prometheus alerting and recording Rules via a Kubernetes
Custom Resource Definition. These Custom Resource Definitions can be
fully validated by the Kubernetes API server during creation time via
automatically generated OpenAPI specifications. Instead of the
restriction of a Prometheus instance to only select Rule definitions
inside its own namespace, the Prometheus specification is extended to
also specify namespaces to look for Rule Custom Resource Definitions
outside its own namespace.

---

Dependent technical changes:

- prometheus: Use github.com/jimmidyson/configmap-reload to reload rules

- prometheus: Remove Prometheus Statefulset deletion function. Starting
with K8s >=1.8 this is handled via OwnerReferences.

- prometheus: Do not add rule files checksum to Prometheus configuration
secret

- prometheus: Update StatefulSet only on relevant changes. Instead of
updating the Prometheus StatefulSet on every `sync()` run, only update
it if the input parameters to `makeStatefulSet` change.  Enforce this
via a checksum of the parameters which is saved inside the annotations
of the statefulset.

- e2e/prometheus: Check how often resources (Secret, ConfigMap,
Prometheus CRD, Service) are updated to enforce that Prometheus Operator
only updated created resources if necessary.

- contrib/prometheus-config-reloader: Remove logic to retriev K8s
ConfigMaps. These are mounted into the pod right away now.

According to the man pages of `rm` and the `-f` option:
> Attempt to remove the files without prompting for confirma- tion,
> regardless of the file's permissions.  If the file does not exist, do
> not display a diagnostic message or modify the exit status to reflect an
> error.  The -f option overrides any previous -i options.

This patch prevents the `build.sh` script from failing if files do not
exist when attempting to delete them.

* kube-prometheus: fix alert rule K8SManyNodesNotReady

* fix alert "K8SManyNodesNotReady" in helm templates & make generate

* Use sync_kube_prometheus.py to make rules in helm in sync

kube-prometheus: Remove hard-coded Prometheus Operator version

The addon resizer was referring to an incorrect role binding and was unable to
access the API.  This changes the rolebinding name to refer to the correctly
defined rolebinding.

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