comment-out seed.js because it's no longer required

Reference: https://github.com/HabitRPG/habitrpg/issues/3852#issuecomment-55334572 (Tyler's comment)

BTW, I would REALLY like to remove almost all the content in README.md and replace it with a link to http://habitrpg.wikia.com/wiki/Setting_up_HabitRPG_locally which contains the same instructions but improved and linkified. Better to have one location for instructions, not two that both need to be updated. I'll do that in a few days if no one objects.