Image download now threaded in the background for packs. This means you
may scroll and launch while images are downloading.

Signed-off-by: Dalton Pelc <daltonjpelc@gmail.com>
Conflicts:
	src/main/java/org/spoutcraft/launcher/skin/components/BackgroundImage.java
	src/main/java/org/spoutcraft/launcher/technic/PackInfo.java
	src/main/java/org/spoutcraft/launcher/technic/skin/ModpackSelector.java
Made the creeper fade-in with background fade-in.

Signed-off-by: Dalton Pelc <daltonjpelc@gmail.com>
Conflicts:
	src/main/java/org/spoutcraft/launcher/skin/components/BackgroundImage.java
	src/main/java/org/spoutcraft/launcher/technic/PackInfo.java
Moved avatars to subfolder in assets

Signed-off-by: Dalton Pelc <daltonjpelc@gmail.com>