Rounds off the corners of the image (to transparent for PNG output)
URL
http://api.imgble.com/rounded-corners|<x>|<y>/http://mydomain.com/myimage.jpg
Parameters
<x> is the horizontal radius of the curve
<y> is the vertical radius
Example
http://api.imgble.com/rounded-corners|15|15/http://farm1.static.flickr.com/57/197881059_aeb724b1cf.jpg
