upgrade express from 3.x to 4.x

I created this pull request for the review of the upgrade changes.
Dude! You should not be checking in secrets. Did you notice this before you
pushed the code to github? Either way, what are you thinking? :)

Please change all tokens in this file to nonsense values that the user will
obviously need to change (like I did). then regenerate all your tokens
because they're most likely already crawled into the internet. (This is a
public project)