Makes an image square based on it's longest size, adding a white border plus an additional border all the way around
- Works on every image present in the directory it's called
- arg 1: the location of the files
- arg 2 (optional): the border to use. If none present the default is 50
- arg 3 (optional): a string of the color ie "black" "blue" etc. Based on Pillow Imaging colors. If none present the default is white