WIP: Populate league with default teams

@ShaiNirShado 

I'm starting with a spec to fill a new league with 22 teams (20 players, 1 commish, 1 user.). So far, so good, but I'm not sure how to add the 'type'. I may as well also add here that if I were to change Special column to Type or something of the, sort, do I just ned to change the model and then rebuild the database?

Next step after this is to apply similar methods to make 22 default teams in a league. I'm going to assume the league owner will be able to change their names as he sees fit. Do we want to use the default MLB teams here?
A) Having the teamArray variable be global to the whole league controller seems dangerous, particularly if we want to populate more than one league. teamArray should definitely be scoped to populateLeague here.
B) By the same token fillArray function doesn't do all that much -- there's no reason you can't take that code and put it directly in your for loop. If you wanted to avoid passing 3 arguments into that function, my advice would be to create the JSON description of the team in populateLeague and pass that into fillArray. However, at that point fillArray becomes just a wrapper around teamArray.push, so I just wouldn't have a separate function here.
C) Rather than looping over an integer, you can loop over each of member of the userTeams array with a forEach loop. I've been using a utility library called lodash that has numerous wonderful functions; the relevant documentation is here: https://lodash.com/docs#forEach
Using lodash (which the league controller already has access to through the variable _) you can access a lot of the nice collection-manipulating functions you may have used in Ruby.