k8s: Add virtual environment for testing

k8s: Add virtual environment for testing

This patch adds simplified ONAP deployment environment (Kubernetes
cluster managed by Rancher). Its purpose is to provide cluster defaults
for inspection without the need to access actual ONAP application
deployment.

Default node customization scripts were extracted
("tools/get_customization_scripts.sh" run within "tools/imported/"
directory) from official documentation [1] and imported here in order
not to introduce runtime online dependencies.

This environment should probably be migrated in future to more
appropriate place like devtool [2] (or at least use the same Vagrant
boxes).

[1] https://docs.onap.org/en/casablanca/submodules/oom.git/docs/oom_setup_kubernetes_rancher.html
[2] https://git.onap.org/integration/devtool

Issue-ID: SECCOM-235
Change-Id: I57f9f3caac0e8b391e9ed480f6bebba98e006882
Signed-off-by: Pawel Wieczorek <p.wieczorek2@samsung.com>