Truck creation reviews

I want to resolve #4 and resolve #5 with a few commits that make a chunk of works!


You can take advantage of some of the niceties of Active Record by rewriting this section like this:

```ruby
def create
  @food_truck = FoodTruck.find(params[:food_truck_id])
  @review = @food_truck.reviews.build(review_params)
  @review.user = current_user

  if @review.save
    # blah blah blah
  end
end
```