Add IND_DEALER_BADGE pseudo-badge

This allows people to register with Dealer ribbons through the regular
pre-reg form by selecting a checkbox.
Update confirmation page

Noticed that the confirm page didn't have the full address or the
interests turned off. Fixed this because AC will be using this page for
staff reg.
Add link to convention store

Adds a message for purchasing dealer tables to the payment confirmation
page.

Since there's no longer an attendee object, this message simply displays
for everyone.
Fix dealer checkbox state

Fixes the dealer checkbox to reflect the status of the attendee, not the
browser cache.
Minor fix to if statement

There ended up being two if clauses that did the exact same thing, so
now they're combined.
Fix merge conflicts
Merge pull request #659 from magfest/add_dealer_option

Add dealer checkbox to pre-reg form