Return self-contained kubeconfig file

Using `bx cs cluster-config id` I can get the `kubeconfig` file, which in my case looks like:

apiVersion: v1
clusters:
- name: bdeng_cluster
cluster:
certificate-authority: ca-prod-dal12-my_cluster.pem
server: https://my_ip:23384
contexts:
- name: bdeng_cluster
context:
cluster: bdeng_cluster
user: https://iam.ng.bluemix.net/kubernetes#my_id
namespace: default
current-context: bdeng_cluster
kind: Config
users:
- name: https://iam.ng.bluemix.net/kubernetes#my_id
user:
auth-provider:
name: oidc
config:
client-id: bx
client-secret: bx
id-token: eyJraW...

It would be useful to have the content of `ca-prod-dal12-my_cluster.pem` rather than a reference to the file.
Would it be possible to support that kind of file?