KUBECONFIG merges are not working

[fsniper]

kubectl has a feature to merge kubeconfigs on the fly via a KUBECONFIG env variable. This is not working with click.

How to reproduce:

$ export KUBECONFIG=cluster-merge:cluster-config:cluster2-config
$ kubectl config get-contexts
CURRENT NAME CLUSTER AUTHINFO NAMESPACE
* cluster1 cluster1 cluster1
cluster2 cluster2 cluster2
$ click
Could not open config file at 'xxxx/.kube/click.config': No such file or directory (os error 2). Using default values
Could not load kubernetes config: 'cluster-merge:cluster-config:cluster2-config'. Cannot continue.  Error was: entity not found

[kirikaza]

Looks like a duplicate of #49