I know you are looking for a software solution but you might consider a hardware solution such as the olloclip. http://www.olloclip.com/ you might want to check ebay and amazon etc for better prices but there are cheap copies out there too.
You cannot get the fisheye lens without an actual hardware fisheye lens. You can edit it to add distortion, but it simply looks strange because the field of view is off (fish eye lens' will simulate roughly human eyesight, 170º field of view). Your average camera, with a focal length of 18mm will have a field of view of around 65º. There simply is no way to 'edit' field of view.