Upgraded from 99c19923, branch release-3.0.
This required fetching or upgrading the following:
* k8s.io/api to kubernetes-1.9.1
* k8s.io/apimachinery to kubernetes-1.9.1
* github.com/juju/ratelimit to 1.0.1
* github.com/spf13/pflag to 4c012f6d
Also, update Scope's imports/function calls to be compatible with the new client.
We will use this code to execute the code in some process' network
namespace.
I did the vendoring a bit differently, as gvt seems to be a bit dumb
about getting dependencies for test packages (it tried to vendor
ginkgo and gomega, since cni tests are using it).
Also, instead of vendoring golang.org/x/sys as
github.com/containernetworking/cni/vendor/golang.org/x/sys I moved it
to scope's vendor directory.