update to version 0.0.2, change to use express 4.x

I have updated your microblog to use express 4.x, but need your help to check the '/' page, I encounter "title is not defined" error, and couldn't find anything wrong.
I'm new to Node.js, even Javascript, and hope the changes is acceptable for you.
Thanks and kindly wait for your reply.
BTW, your book is very good for beginners like me.