Allow configuration of a custom /etc/resolv.conf for kubelet.

* Enforce a etcd-proxy role to a k8s-cluster group members. This
provides an HA layout for all of the k8s cluster internal clients.
* Proxies to be run on each node in the group as a separate etcd
instances with a readwrite proxy mode and listen the given endpoint,
which is either the access_ip:2379 or the localhost:2379.
* A notion for the 'kube_etcd_multiaccess' is: ignore endpoints and
loadbalancers and use the etcd members IPs as a comma-separated
list. Otherwise, clients shall use the local endpoint provided by a
etcd-proxy instances on each etcd node. A Netwroking plugins always
use that access mode.
* Fix apiserver's etcd servers args to use the etcd_access_endpoint.
* Fix networking plugins flannel/calico to use the etcd_endpoint.
* Fix name env var for non masters to be set as well.
* Fix etcd_client_url was not used anywhere and other etcd_* facts
evaluation was duplicated in a few places.
* Define proxy modes only in the env file, if not a master. Del
an automatic proxy mode decisions for etcd nodes in init/unit scripts.
* Use Wants= instead of Requires= as "This is the recommended way to
hook start-up of one unit to the start-up of another unit"
* Make apiserver/calico Wants= etcd-proxy to keep it always up

Signed-off-by: Bogdan Dobrelya <bdobrelia@mirantis.com>
Co-authored-by: Matthew Mosesohn <mmosesohn@mirantis.com>

Defaults to false. Use with v1.3 only.

Signed-off-by: Bogdan Dobrelya <bdobrelia@mirantis.com>

This was missing from commit c4c312c2

Systemd reload before reload kubelet was failing because its definition was before "restart kubelet". Its definition should be after the notify hook.

This should make things a little more composable,
by making these roles meta roles that perform no
actions by default we allow each role to own its own
resources.

Kubernetes API server has an option:

```
--advertise-address=<nil>: The IP address on which to advertise the apiserver to members of the cluster. This address must be reachable by the rest of the cluster. If blank, the --bind-address will be used. If --bind-address is unspecified, the host's default interface will be used.
```

kargo does not set --bind-address, thus it binds to eth0, in vagrant and similar
environments this causes issues because nodes cannot talk to eachother over eth0.

This sets `--advertise-address` to `ip` if its set, otherwise the default behavior
of is persisted by using `ansible_default_ipv4.address`.

check_certs task "Check_certs | Set 'sync_certs' to true" was failing
due to the dict not existing, this sets defaults that allows the
correct behavior of the conditionals.

This allows you to simply run `vagrant up` to get a 3 node HA cluster.

* Creates a dynamic inventory and uses the inventory/group_vars/all.yml
* commented lines in inventory.example so that ansible doesn't try to use it.
* added requirements.txt to give easy way to install ansible/ipaddr
* added gitignore files to stop attempts to save unwated files
* changed `Check if kube-system exists` to `failed_when: false` instead of
`ignore_errors`

cosmetic

as per @smana request

add option for generic