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.

I accidently left in the old download URL for coreos
even after I switched the box name to be ubuntu, it
worked fine for me because I already had that box
locally so it didn't try to download.  This should
resolve this by using the official bento/ubuntu-14.04
box which is a nice minimal image.

We also allow the default behaviour of sharing folder to VMs

By doing this we can stage our download files in a shared location
and speed up subsequent runs significantly.

Finally will create more verbose documentation.

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`