and correct checksums

Signed-off-by: Bogdan Dobrelya <bdobrelia@mirantis.com>

Move the variable kube_version to defaults to have the possibility to overwrite it via group_vars inventory if needed.

Save/push/load containers if only download.enabled and download.container

Signed-off-by: Bogdan Dobrelya <bdobrelia@mirantis.com>

"else omit" is causing problems in this expression. Replacing
it with more strict "inventory_hostname" fixes the issue and
handles `download_run_once` as expected.

Closes issue #514

* Add the retry_stagger var to tweak push and retry time strategies.
* Add large deployments related docs.

Signed-off-by: Bogdan Dobrelya <bdobrelia@mirantis.com>

Signed-off-by: Bogdan Dobrelya <bdobrelia@mirantis.com>

Move version/repo vars to download role.
Add container to download params, which overrides url/source_url,
if enabled.
Fix networking plugins download depending on kube_network_plugin.

Signed-off-by: Bogdan Dobrelya <bdobrelia@mirantis.com>

Fixes #450

Nearly the last stage of source all components to containers.
Kubectl will be called from hyperkube image.

Remaining tasks:
 * Move kube_version variable to kubernetes/preinstall
 * Drop placeholder download.nothing requirement

kubelet via docker
kube-apiserver as a static pod

Fixed etcd service start to be more tolerant of slow start.

Workaround for kube_version to stay in download role, but not
download an files by creating a new "nothing" download entry.

Improves upgradability of calicoctl by leveraging docker tags.

This should make things a little more composable,
by making these roles meta roles that perform no
actions by default we allow each role to own its own
resources.

using a shared folder can cause race conditions for the download
role as it tries to download files on all the nodes to the same
shared path.  This adds a flag to run the tasks in the download
role on just one node.