Vagrant back to vboxfs

Changing back to vboxfs since I couldn't get it to install as an SMB
share.
Replace hardcoded data in prereg messages

Dynamic event and prereg open dates, plus a fix for events without
years.
Reverting prereg_takedown value

I had messed with prereg_takedown for testing, forgot to put it back.
Update README.md
delete graph data
Merge branch 'master' of https://github.com/magfest/ubersystem
Merge pull request #306 from magfest/bugfix_reg_check

Bugfix reg check
magstock: remove ability for new people to sign up for shirt pre-orders
if you already have a shirt selected, it'll let you see that.
the entire shirt/merch system in uber needs to be ripped out and redone as a shopping cart or something
Merge pull request #310 from magfest/shirt_disable

magstock: remove ability for new people to sign up for shirt pre-orders
Merge branch 'master' into develop
Merge branch 'master' into develop