publisher: append Cocoa style suffixes depending on resolution for Sprite Kit projects

Sprite Kit won't recognize a "hd" file unless it carries the @2x suffix. This fix appends @2x, ~ipad and @2x~ipad suffixes for phonehd, tablet and tablethd resolutions of published image files.

A corresponding fix in CCFileUtils (SpriteBuilder+SK) was also necessary to make this work.