vendor: update containernetworking/cni and add containernetworking/plugins

Updated containernetworking/cni moves pkg/ns to containernetworking/plugins
so we need that now too.

vendor/github.com/containernetworking/plugins/build.sh

@@ -0,0 +1,30 @@
+#!/usr/bin/env bash
+set -e
+cd $(dirname "$0")
+
+if [ "$(uname)" == "Darwin" ]; then
+	export GOOS="${GOOS:-linux}"
+fi
+
+ORG_PATH="github.com/containernetworking"
+export REPO_PATH="${ORG_PATH}/plugins"
+
+if [ ! -h gopath/src/${REPO_PATH} ]; then
+	mkdir -p gopath/src/${ORG_PATH}
+	ln -s ../../../.. gopath/src/${REPO_PATH} || exit 255
+fi
+
+export GOPATH=${PWD}/gopath
+export GO="${GO:-go}"
+
+mkdir -p "${PWD}/bin"
+
+echo "Building plugins"
+PLUGINS="plugins/meta/* plugins/main/* plugins/ipam/* plugins/sample"
+for d in $PLUGINS; do
+	if [ -d "$d" ]; then
+		plugin="$(basename "$d")"
+		echo "  $plugin"
+		$GO build -o "${PWD}/bin/$plugin" "$@" "$REPO_PATH"/$d
+	fi
+done