Port networking to CNI

Replaced netns utility with CNI plugins to create a bridge network
and allow communication between containers with firewall plugin.

Overwrite the CNI config in case it exists. Allow updating the config
on new versions.

Signed-off-by: Carlos de Paula <me@carlosedp.com>

vendor/github.com/google/uuid/node_net.go

@@ -0,0 +1,33 @@
+// Copyright 2017 Google Inc.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build !js
+
+package uuid
+
+import "net"
+
+var interfaces []net.Interface // cached list of interfaces
+
+// getHardwareInterface returns the name and hardware address of interface name.
+// If name is "" then the name and hardware address of one of the system's
+// interfaces is returned.  If no interfaces are found (name does not exist or
+// there are no interfaces) then "", nil is returned.
+//
+// Only addresses of at least 6 bytes are returned.
+func getHardwareInterface(name string) (string, []byte) {
+	if interfaces == nil {
+		var err error
+		interfaces, err = net.Interfaces()
+		if err != nil {
+			return "", nil
+		}
+	}
+	for _, ifs := range interfaces {
+		if len(ifs.HardwareAddr) >= 6 && (name == "" || name == ifs.Name) {
+			return ifs.Name, ifs.HardwareAddr
+		}
+	}
+	return "", nil
+}