Update kuryr/demo container to support UDP server.
After this change, the kuryr/demo image runs both HTTP and UDP
servers.
The listeners ports values could be configured using pod's
environment variables.
And in addition, a simple udp client binary tool was added to
image, to use it, you should run :
udp_client <server's_ip> <server's port>
Change-Id: I9f2f2ad3273f947fecb776c0f56f6829df81aa67
Yossi Boaron