Updates passport-twitter/examples 

Hello, 
I'm submitting this pull request for two reasons: First, I would like to add an example application to the passport-twitter repository; Second, I want to remove the current example application in passport-twitter.

The current example has several egregious errors stemming from its design:

1) package.json accepts the latest version of all packages (Express 4 is being installed), but the example application was written for an earlier version of Express 3: 
![screen shot 2014-05-04 at 2 35 17 pm](https://cloud.githubusercontent.com/assets/6133673/2874220/9210e9a6-d3dc-11e3-8e63-b98a8ca6faff.png)

2) Updating package.json to a recent version of Express 3 leads to more issues, such as an incorrect instantiation of a server: 

![screen shot 2014-05-04 at 2 34 37 pm](https://cloud.githubusercontent.com/assets/6133673/2874225/cd849f00-d3dc-11e3-9ce2-c0a4e3b032be.png)

3) There are several other issues....