Use image family for picking latest coreos image
Update python deps

Also update to ansible 2.3.2

Required for an RPM package builds with the contrib/ansible-kubespray.spec

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

- Fix when clauses in various places
- Update requirements.txt
- Fix README.md

Signed-off-by: Sergii Golovatiuk <sgolovatiuk@mirantis.com>

ansible 2.2.2.0 has an [issue]() that causes problems for kargo:

```
(env) kargo ᐅ env/bin/ansible-playbook upgrade-cluster.yml 
ERROR! Unexpected Exception: 'Host' object has no attribute 'remove_group'
```

Pinning ansible to 2.2.1.0 resolved this for me.

Ansible 2.2.1 requires jinja2<2.9, see <https://github.com/ansible/ansible/blob/v2.2.1.0-1/setup.py#L25>,
but without explicit limiting upper jinja2 version here pip ignores
Ansible requirements and installs latest available jinja2
(pip is not very smart here), which is incompatible with with
Ansible 2.2.1.
With incompatible jinja2 version "ansible-vault create" (and probably other parts)
fails with:
  ERROR! Unexpected Exception: The 'jinja2<2.9' distribution was not found 
  and is required by ansible
This upper limit should be removed in 2.2.2 release, see:
<https://github.com/ansible/ansible/commit/978311bf3f91dae5806ab72b665b0937adce38ad>

Jinja 2.* releases are published under `Jinja2` name.

Added Jinja 2.8 Requirements to docs and pip requirements file which
is needed to run the current Ansible Playbooks.

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`