This change adds additional test coverage for the kubecfg
command. There is now a test for the case when the auth info
file does not exist. LoadAuthInfo tests have been refactored
to use table testing.
Also make the output and validation of input better for kubecfg api calls.
Kubecfg will now display a usage argument if the URL is incorrect or an
unrecognized storage type is passed.
Check for 1 path segment on create/list, 2 on update/delete, and
allow any number of path segments on get (for now).
Also pretty prints the list of actual types that are supported for
create/update, which today corresponds to the list of types that
are supported period.
