Fix issue about setting customized cluster name when using kubespray

[jianzj]

openstack

When using kubespray openstack to initialize environment and deploy
kubernetes cluster, if you want to setup a cluster name with
--cluster-name, you will always receive errors like

TASK [Create nodes network ports]
**********************************************
failed: [localhost] (item=k8s-phenomenal-ootp8f) => {"failed": true,
"item": "k8s-phenomenal-ootp8f", "msg": "Security group:
k8s-phenomenal-69k17f, was not found"}
failed: [localhost] (item=k8s-phenomenal-ystmto) => {"failed": true,
"item": "k8s-phenomenal-ystmto", "msg": "Security group:
k8s-phenomenal-69k17f, was not found"}
failed: [localhost] (item=k8s-phenomenal-k2f8sf) => {"failed": true,
"item": "k8s-phenomenal-k2f8sf", "msg": "Security group:
k8s-phenomenal-69k17f, was not found"}

That is because security group name is redefined and security group is
not created with these names.

These is one issue existing,
#64

I did some code changes, which cluster_name will be changed at the first
place when customer set a new one.

Please help to review and let me know if anything that I could update or
improve.

[Smana]

Thank you and sorry i didn't do many tests on openstack