Three demo files and a help file for oob oauth login

Examples of how to use twitteroauth completely from the commandline (using the oob callback), including documentation.
This can be used from behind a firewall (i.e. no need to put any files on a live web server).

The required functionality is already all in twitteroauth, but it is very hard to find full working examples, so I think a small number of people will find this very useful. It would have saved me 2-3 hours.

I'm happy to merge oob_readme.txt into the DOCUMENTATION file if you think that makes more sense.