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`

.gitignore

@@ -0,0 +1,3 @@
+.vagrant
+*.retry
+inventory/vagrant_ansible_inventory