DinoDex refactor

Refactored DinoDex based on comments from first pull request.
probably no need to have the variable `launch`

Also, just a thought, you could rename the command_line.rb to dino_dex_runner.rb (DinoDexRunner) and just include the `new(...)` outside of the class definition. So doing `$ ruby dino_dex_runner.rb` would run (since this class is really small)

But maybe you want the separation, and that's totally cool with me