Update README

* Change the link to our new support forums
* Change the link to contriburo infomation
* Move Travis CI badge to top
update docs to reflect security best practices

Thanks to Stefano di Paola and Dmitry Savintsev for letting us know
about a potential security vulnerability in one of our examples. See
http://blog.mindedsecurity.com/2009/05/http-parameter-pollution-new-web-attack.html
for more specifics.
remove notes with potential to confuse the reader

https://github.com/yui/yui3/commit/66d93224c54944170f3b2642060a11c1664851bd
Merge pull request #1128 from okuryu/readme

Update README