kube-prometheus: Run node-exporter in host network

Node exporter needs to run in the host network, not in the pod network
in order to pick up network metrics of the node.

*: Refactor build system

- Move prometheus-config-reloader to cmd/
- Refactor Makefile & contrib/kube-prometheus/Makefile
- Only execute a target if its dependencies changed
  - Create empty target file for docker builds
- Replace promu with plain static `go build`

kube-prometheus: Use 1 ConfigMap per Grafana dashboard

NodeDiskRunningFull ignore etc files mountpoints

*: Use all jsonnet from master branch

Added section about grafana config

* Ignores '/etc/resolv.conf', '/etc/hosts' and '/etc/hostname' mountpoints
* Otherwise 3 additional alerts are generated

89fc4e306972604eba2dcb961a6d29cc27a668ad introduced the new Prometheus
rule file custom resource definition. This patch adjusts the
kube-prometheus project to use the new custom resource definition.

kube-prometheus: Remove duplicate unused files

afe9711ce2ef5dd0e0b5091f921ae9bc0aab3711 introduced
contrib/kube-prometheus/0prometheus-operator-clusterRole.yaml and
contrib/kube-prometheus/0prometheus-operator-deployment.yaml by mistake.

rbac: Remove Third Party Resources rules

Since PR 460 [1] the Prometheus Operator is using Kubernetes Custom Resource
Definitions instead of Kubernetes Third Party Resources. Permissions to
handle Third Party Resources in the RBAC rules of the Prometheus
Operator is thereby obsolete.

[1] https://github.com/coreos/prometheus-operator/pull/460

prometheus: Enable live migration of rule configmaps to rule file crds

With this patch the Prometheus Operator checks if there are any
Kubernetes ConfigMaps inside the Prometheus namespace which fullfill the
`Spec.RuleSelector` requirement. If so, it creates a RuleFile for each
key in the `ConfigMap.Spec.Data` map inside the Prometheus namespace.

Adds proxy_url to v1.Endpoint. Fixes #1385

Migrate alerts

Make certgen work on OSX

These alerts will be vendored in the future through jsonnet-bundler
directly from the etcd repository.