* Adds support for Multus (multiple interfaces) CNI plugin

Multus is a latin word for "Multi". As the name suggests, it acts as a
Multi plugin in Kubernetes and provides multiple network interface
support in a pod. Multus uses the concept of invoking delegates by
grouping multiple plugins into delegates and invoking them in the
sequential order of the CNI configuration file provided in json format.

* Change CNI version (0.1.0->0.3.1) of Contiv to be compatible with Multus

[contrib/terraform/openstack] Allow user defined port ranges for worker security group

fix modify the way of the command 'yum remove xxx', e.g. docker-selin…

* [contrib/terraform/openstack] Add worker_allowed_ports

  Allow user to define in terraform template which ports and remote
  IPs that are allowed to access worker nodes. This is useful when you
  don't want to open up whole NodePort range to the outside world, or
  ports outside NodePort range.

When using resolvconf_mode host_resolvconf, there is an early DNS
config stage where Kubernetes cluster DNS is not injected for host
DNS intially. Later, the cluster DNS is enabled, but we do not
need to run every task from the kubernetes/preinstall role.

* Added the missing environment for proxy for get_url

* Update upgrade.yml

* Fixed spaces

* Fixed spaces

* Update upgrade.yml

Upstream Changes:

   - coredns v1.2.5 (https://github.com/coredns/coredns/releases/tag/v1.2.5)

NOTE:

   - Switch image repo to https://hub.docker.com/r/coredns/coredns/ (https://github.com/kubernetes-incubator/kubespray/pull/3595#issuecomment-433962973)

Standalone etcd nodes do not generate node-$hostname certs and do
not need this serial calculated.

Correct the wrong words

fix typo doesnt -> doesn't

fix typos in line 114 and 116: doesnt -> doesn't

Only exclude buggy Ansible v2.7.0 (https://github.com/ansible/ansible/issues/46600#issuecomment-433863628)

Fixup #3589

appropiate->appropriate

fix modify the way of the command 'yum remove xxx', e.g. docker-selinux and docker-engine-selinux packages

Correct the wrong word

typo fix about officially

Signed-off-by: Yongxin Li <yxli@alauda.io>

Fix some typos

Signed-off-by: Rui Cao <ruicao@alauda.io>

Revert "CoreDNS v1.2.5 (#3595)"

* Add an 'access_ip' for openstack resources to the terraform inventory builder script

* Update Openstack README

* Only use ipv4

* If there's a floating IP assigned to an openstack instance, use that for access_ip

This reverts commit 8ba6b601.

* do it like in kubernetes/secrets

* fix indentation

* processed comments

* missed one, sorry

* trailing space fix

Fix typo

need set hostname by kubeadm

Update vsphere.md