openstack: create cinder VG if user set

Signed-off-by: Dunrong Huang <riegamaths@gmail.com>
fetch IP address if user do not set it before packstack!

Signed-off-by: Dunrong Huang <riegamaths@gmail.com>
network: rework ask_user in module openstack

this func is so ugly, and when role is computer, this function
can not be reused, so rework it

Signed-off-by: Dunrong Huang <riegamaths@gmail.com>
make role of computer work

Signed-off-by: Dunrong Huang <riegamaths@gmail.com>
network: disable NetworkManager and enable network

Signed-off-by: Dunrong Huang <riegamaths@gmail.com>