Add the load of the races respository files.

The main idea here is add some convention to add new content data for races, items, character classes, backgrounds and etc.

I used a little bit of meta programming. XD
The thing that is bothering me is a huge file. I'm feel little bit confused. Today with 4 races we have more than 2 hundreds lines, with all 9 or 12 races will increase to thousand maybe. This will happen to character classes, background, items and etc. Adding a new class you must keep the order on the array too.

The idea of divide in smaller files: have focused files for each item.
The idea of auto load the constants of the each file: become easier to add new items(because is  just add a file on the repository directory).

I tried to `RaceRepository.constants`, but the rails auto load will not load the each file constant until you try to access them. That why I came with the idea of read the repository directory and access them. The Rails auto load just not auto loads the Class stuff, it loads the constant too.