Added more things to x86_64 image.

Some preference apps, mount_server and AboutSystem. Removed the check
for x86_64 in the boot script, the normal path through the script will
work now. Also removed a temporary hack to workaround AboutSystem not
being there in build_haiku_image.

data/system/boot/Bootscript

@@ -116,14 +116,6 @@ if [ "$SAFEMODE" != "yes" ]; then
 	waitfor _input_server_event_loop_		# wait for input devices
 fi
 
-# TODO: remove this when x86_64 is more complete.
-if [ "$(uname -m)" = "x86_64" ]; then
-	cd /boot/home
-	launch system/Tracker
-	launch system/Deskbar
-	exit
-fi
-
 # Now ask the user if he wants to run the Installer or continue to the Desktop.
 if [ "$isReadOnly" = "yes" ]; then
 	# Create Installer link (using the write overlay)