Download images as dependencies of roles

Pre download all required container images as roles' deps.
Drop unused flannel-server-helper images pre download.
Improve pods creation post-install test pre downloaded busybox.
Improve logs collection script with kubectl describe, fix sudo/etcd/weave
commands.

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

tests/testcases/020_check-create-pod.yml

@@ -1,6 +1,10 @@
 ---
 - hosts: node1
 
+  vars:
+    test_image_repo: busybox
+    test_image_tag: latest
+
   tasks:
 
   - name: Force binaries directory for CoreOS
@@ -13,7 +17,7 @@
     when: ansible_os_family != "CoreOS"
 
   - name: Run a replica controller composed of 2 pods
-    shell: "{{bin_dir}}/kubectl run test --image=busybox --replicas=2 --command -- tail -f /dev/null"
+    shell: "{{bin_dir}}/kubectl run test --image={{test_image_repo}}:{{test_image_tag}} --replicas=2 --command -- tail -f /dev/null"
 
   - name: Pods are running
     shell: "{{bin_dir}}/kubectl get pods --no-headers -o json"