Add a new config option, an example:
trusted_cidrs = 127.0.0.1/32,22.214.171.124/32
If trusted_cidrs is empty list, the local IP CIDR will be used.
The pod in qinling namespace can only be accessed by the CIDRs
This change also modifies the devstack installation script to re-use
k8s api server etcd client certs as qinling etcd certs, and use TLS to
connect with etcd by default in devstack.
Because the etcd server in k8s 1.10 doesn't support https by default, this
patch also upgrade k8s to 1.11 in devstack installation.