Mininet alpha release license

(c) 2009-2010 Bob Lantz and Brandon Heller

Mininet is currently in *limited alpha release*. We encourage you to
experiment with it and hope that you will provide us with feedback on
features, documentation, and how you're using it. We plan to make it
available publicly via a GPL or BSD license (probably in April), but please
don't distribute the code or URLs yet! The feedback you provide will help
us improve Mininet for general release.