fix k8 aio flavor undefined variable

fix k8 aio flavor undefined variable

1. fix error that kube_require_packages is undefined
2. add "remote_user: root" in configure-kubenet.yml
   if don't add this, it will have issue to connect host.
   fatal: [opnfv]:UNREACHABLE! => {"changed": false, "msg":
   "Failed to connect to thehost via ssh: Permission denied (publickey,password).\r\n",
   "unreachable": true"}

installer-type:kubespray
deploy-scenario:k8-nosdn-nofeature

Change-Id: Ia8d1980ad18375c0cff3a97b284b0f53d7539e23
Signed-off-by: wutianwei <wutianwei1@huawei.com>