Changes: Minor refactoring of image cache generator.
Changes: Minor refactoring of image cache generator.

RevBy: Kuisma Salonen, Armin Berres.

Details: ImageResource class cannot have a static saveToFsCache method, due to unique key generator.

nemomobile-graveyard/libmeegotouch,nemomobile-graveyard/libmeegotouch,nemomobile-graveyard/libmeegotouch,nemomobile-graveyard/libmeegotouch,nemomobile-graveyard/libmeegotouch,nemomobile-graveyard/libmeegotouch