IMPORTANT NOTE
If you are wanting to play with this mod get only the files in the normal version. If you plan to showcase or otherwise document this mod for a video or something use the files in the "Increased Spawning" folder, as it will make it easier to find my mobs (Single Player Commands doesn't work with my mod). By easier I mean they will spawn often, during the day, in large groups, and with the generation of the terrain (like animals) which I doubt will be fun for the average player.

Another note:
If your config file seems not to work (creepers that you want to spawn don't or vice versa) a good solution is to delete it and run minecraft again, then close minecraft and edit the file to your liking.