Update version 0.7.8 -> 0.7.9

Bonus: remove the URL of RFC 6455 from description. It's too long.
Review URL: https://codereview.appspot.com/7690045

git-svn-id: http://pywebsocket.googlecode.com/svn/trunk@742 4ff78f4a-9131-11de-b045-6380ec9940d4