DinoDex 9/8/2014

1. this could be done with a `map` instead of an `each`
2. this just returns HEADERS downcased. Is a separate method necessary? you could just define them in another constant instead. 
3. along those lines, is there some way you could consolidate `Dinosaur::HEADERS` and `Dinosaur#fields` into one array, given that the only difference between them is capitalization?