Add native Vagrant support

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`

README.md

@@ -9,6 +9,8 @@
 - Support most popular **Linux distributions**
 - **Continuous integration tests**
 
+To create a cluster in vagrant simply run `vagrant up`
+
 For an easy way to use it, check out [**kargo-cli**](https://github.com/kubespray/kargo-cli) </br>
 A complete **documentation** can be found [**here**](https://docs.kubespray.io)