Feature: implement scale/zoom on both resize and crop #25
Description
Scale/zoom/enlarge is currently its own directive. Scale should be implemented, in such that, it can be use for both resize and crop. Change ratio_max to scale_max with 1 as default value; if scale is set to any value greater than 1, it would enable scaling of image with resize, crop, rotate, and etc...
image_filter_scale_max 2;