suggestion: only make diffImage when the images don't match

[jpratt2]

As a suggestion, I suggest that the diff image doesn't need to be created unless there is a difference.
Currently, this will create a diffImage.png every time, even if there is no difference.
//Shutterbug.shootPage(driver,ScrollStrategy.WHOLE_PAGE).equalsWithDiff(expectedImage,"observed\diffImage");

[jpratt2]

Thank you for fixing this.