I don't know if this could help, but I found a mod that solves this problem specifically, including all of the problems detailed here. (Chest, hand and mobs lighting glitches). http://www.minecraftforum.net/topic/1547522-162-164-minecraftlfm-fixes-colored-signs-entity-rendering-and-much-more-4000-downloads/
Arturo Federico
I don't know if this could help, but I found a mod that solves this problem specifically, including all of the problems detailed here. (Chest, hand and mobs lighting glitches). http://www.minecraftforum.net/topic/1547522-162-164-minecraftlfm-fixes-colored-signs-entity-rendering-and-much-more-4000-downloads/