Support kube-proxy data plane

This plugin provides kube-proxy data plane on user space,
which is used to replace linux kernal's kube-proxy based on iptables.
The idea is largely inspired from VPP LB plugin.

Currently, kube-proxy plugin supports three service types:
1) Cluster IP plus Port: support any protocols, including TCP, UDP.
2) Node IP plus Node Port: currently only support UDP.
3) External Load Balancer.

Please refer to kp_plugin_doc.md for details.

Change-Id: I36690e417dd26ad5ec1bd77c7ea4b8100416cac6
Signed-off-by: Hongjun Ni <hongjun.ni@intel.com>
diff --git a/src/configure.ac b/src/configure.ac
index d84a481..b4c0c70 100644
--- a/src/configure.ac
+++ b/src/configure.ac
@@ -215,6 +215,7 @@
 PLUGIN_ENABLED(ila)
 PLUGIN_ENABLED(ioam)
 PLUGIN_ENABLED(ixge)
+PLUGIN_ENABLED(kubeproxy)
 PLUGIN_ENABLED(lb)
 PLUGIN_ENABLED(memif)
 PLUGIN_ENABLED(pppoe)