Folder stuff

Fixes #645 (everyone gets a vesting folder)
Fixes #644 (My Links folder rules properly enforced)

DEPLOYMENT NOTE: To simplify the code and deploy process, I just set it so we create the My Links folder if necessary every time we show the folder list. This is a little inefficient but fine for short-term code, and means you don't have to run anything to create folders when deploying. Also makes sure we don't have to create folders in a bunch of different places when users are promoted.