kubespray

The new version brings the following improvements:
- remove having to resort to python python to limit tags (it it slower than
the sh equivalent as python has a somewhat significant startup time).

- Introduce a concept of min version so that it can only get Kubernetes
version supported by Kubespray.

- Fix an issue with kata changing their file scheme (the arch
  specifically)

- Now download sha256/sha256sum files if provided rather than
  downloading the full file and computing the hash

- A few minor style tweaks

Signed-off-by: Arthur Outhenin-Chalandre <arthur@cri.epita.fr.fr>