Populate csv files within a folder to populate a sport with players, part 1

@ShaiNirShado 

This one gets the most basic functionality that we're looking for. It goes through all csv files in a folder at the root called ```default_players```, then it'll go through the columns as necessary and add them to the database, and add them to the proper sport id. (Format for CSV files are written in the comments).

Next up on the list is to manipulate strings in the csv so this process isn't so troublesome where we have to manually edit all the csvs to this format, and to label rookies. 

As for the other PR, can probably safely close that one (it's mainly for review purposes), but I was wondering if we should just run this populate method when we create the new sport?
findOrCreate() and player.save() both return Promises here -- an object that represents an asynchronous run of code. So you could in theory rephrase this as 
var promise = Player.findOrCreate({player info});
promise.success(function(player,created){ ... });
The function that you're passing into the .success() method is a callback that runs in case the promise doesn't return an error. The code path is essentially forking -- the findOrCreate() function will run in parallel to the code that follows in the JavaScript file. For that reason, the following line's callback() will run before any of the Player objects are created. The error-checking code you have below would therefore have no way of knowing whether a player was successfully created or not.

If that makes sense (or doesn't make sense), I would read up on promises here: https://github.com/petkaantonov/bluebird
This is the promise library that Sequelize uses. If you look at the API Reference, you can also find methods like Promise.map which acts a lot like async.map but plays nicer with Sequelize code.