FIX Image: deleteFormattedImages() regex

Resampled images could include names without a size argument, such as CMSThumbnail-test_image.png.
And also could include names with a size and a hex color code, such as PaddedImage200100FFFFFF-test_image.png.

This makes arguments after the function name optional.
Minor code formatting here, should just be "as" (not capitalized)