Update Krake architecture diagram (include Infrastructure Provider/Controller- #491)

The current architecture diagram, published in the Krake docs here, does not include the #491 components and it is also a little bit outdated (deprecated OpenStack magnum controller is still there) In addition, the arrows from and to components are not correctly used (e.g. Krake API does not communicate (call) the control plane components, so IMO the bidirectional arrow is wrong here)