Remove the hard coded default "fission" namespace that was added in the last PR, replacing it with some logic to figure out where fission is installed and connecting to it if there's exactly one installation. If there is more than one fission installation, error out with a useful message.
Also improve the error message for a missing kubeconfig file.
This makes set up easier for new users. Users can still set
FISSION_NAMESPACE but it will default to "fission". Users can also
still set KUBECONFIG, but it will default to $HOME/.kube/config.
Also, update the post-install chart notes.txt and the install guide to
use "fission function test" as the first step after install. This
means that if there's anything wrong with the setup, the user will see
useful errors instead of "internal server error". Also, they can test
their setup without worrying about nodeports or ingresses or whatever.
All existing functionality of FISSION_URL and FISSION_ROUTER continues
to work.
setting serviceType to ClusterIP as default for fission controller and corresponding changes in fission cli to be able to port-forward the controller pod.
