Update Italian translation
Add findFileInCardText in AMStringUtils to find file references in a
card.
Add findFileInPaths in AMFileUtil to find a file in search paths.
Refactory CardImageGetter to use amFileUtil.findFileInPaths
Display image in an image viewer when long clicking a card with an image.

Also added an option to enable/disable it in the options.
Revert the options. The Long click to view image is not configurable.