Fix for the issue #23

The cause of the horizontal line artifacts was bilinear interpolation in JAI.

Pure Java mode mediaLib is free from this problem. Updating mlibwrapper didn't fix the bug, so I just commented out interp lines in gaussianBlur function.

Note: lightcrafts/src/com/lightcrafts/model/ImageEditor/ContrastMaskOperation.java has almost same code. I haven't checked whether it causes same bug yet.