DinoDex refactor

Refactored DinoDex based on comments from first pull request.
Doing a command line interface is totally cool and increasingly common. However, the command line interface needs to be completely decoupled from your main logic i.e. you need to be able to plug your app logic into a rails app and not need the command line at all. Your command line class 'knows' about `JoesDinos` and `PirateBayDinos`. You can probably remove this knowledge in the command line class