kubespray

* Add download_localhost for the download_run_once mode, which is
  use the ansible host (a travis node for CI case) to store and
  distribute containers across cluster nodes in inventory.
  Defaults to false.
* Rework download_run_once logic to fix idempotency of uploading
  containers.
* For Travis CI, enable docker images caching and run Travis
  workers with sudo enabled as a dependency
* For Travis CI, deploy with download_localhost and download_run_once
  enabled to shourten dev path drastically.
* Add compression for saved container images. Defaults to 'best'.

Signed-off-by: Bogdan Dobrelya <bdobrelia@mirantis.com>
Co-authored-by: Aleksandr Didenko <adidenko@mirantis.com>