Addition of the .creds extension to the credentials files generated by password lookup in order for Ansible not to consider them as inventory files with inventory_ignore_extensions set accordingly (#2446)

This version required changing the previous access model for dashboard completely but it's a change for the better. Docs were updated.

* New login/auth options that use apiserver auth proxying by default
* Requires RBAC in `authorization_modes`
* Only serves over https
* No longer available at https://first_master:6443/ui until apiserver is updated with the https proxy URL:
* Can access from https://first_master:6443/api/v1/namespaces/kube-system/services/https:kubernetes-dashboard:/proxy/#!/login you will be prompted for credentials
* Or you can run 'kubectl proxy' from your local machine to access dashboard in your browser from: http://localhost:8001/api/v1/namespaces/kube-system/services/https:kubernetes-dashboard:/proxy/
* It is recommended to access dashboard from behind a gateway that enforces an authentication token, details and other access options here: https://github.com/kubernetes/dashboard/wiki/Accessing-Dashboard---1.7.X-and-above

* Change deprecated vagrant ansible flag 'sudo' to 'become'

* Emphasize, that the name of the pip_pyton_modules is only considered in coreos

* Remove useless unused variable

* Fix warning when jinja2 template-delimiters used in when statement

There is no need for jinja2 template-delimiters like {{ }} or {% %}
any more. They can just be omitted as described in https://github.com/ansible/ansible/issues/22397

* Fix broken link in getting-started guide

* Disable basic and token auth by default

* Add recommended security params

* allow basic auth to fail in tests

* Enable TLS authentication for kubelet

Signed-off-by: Junaid Ali <junaidali.yahya@gmail.com>

New files: /etc/kubernetes/admin.conf
           /root/.kube/config
           $GITDIR/artifacts/{kubectl,admin.conf}

Optional method to download kubectl and admin.conf if
kubeconfig_lcoalhost is set to true (default false)

* Add kube dashboard, enabled by default

Also add rbac role for kube user

* Update main.yml

Removed unnecessary root user

$IPS only expands to the first ip address in the array:

justin@box:~$ declare -a IPS=(10.10.1.3 10.10.1.4 10.10.1.5)
justin@box:~$ echo $IPS
10.10.1.3
justin@box:~$ echo ${IPS[@]}
10.10.1.3 10.10.1.4 10.10.1.5

Also adds calico-rr group if there are standalone etcd nodes.
Now if there are 50 or more nodes, 3 etcd nodes will be standalone.
If there are 200 or more nodes, 2 kube-masters will be standalone.
If thresholds are exceeded, kube-node group cannot add nodes that
belong to etcd or kube-master groups (according to above statements).

Fix mismatching inventory examples.
Add command examples.
Clarify groups use cases.

Signed-off-by: Bogdan Dobrelya <bogdando@mail.ru>

Signed-off-by: Bogdan Dobrelya <bogdando@mail.ru>

Includes tox support for running unit tests.
Small note added to getting-started guide for using
inventory_builder.py

Also adds manual-only unit test.