fill_access_token

> Added a new method called from ebooks auth that will automatically fill
> a bot's access_token and access_token_secret variables inside ebooks.rb,
> assuming the file is in the same format as the one in /skeleton

It makes me sad that you don't like #50, but I wrote you a method that will make `ebooks auth` automatically insert access token details into `bots.rb`. It only works if users have already typed their bot's usernames in, and if they haven't changed bots.rb (or at least four lines of it) too much from its original form though.