Fix dealer registration page

Prevents the badge_type_label from being used if on the dealer
registration page, because PSEUDO_DEALER_BADGE doesn't seem to have a
label.
Fix 500 error on dealer application submit

There was a 500 error that turned out to be caused by a second "badges"
select field being drawn and hidden on the page. This makes sure they
aren't drawn if is_dealer is true.
Add table options and badge limits

Changes the table options to match AnthroCon's needs. Changes the badge
selection box based on the table selection.
Prevent injection for badges

Catches badge injection serverside so enterprising dealers can't
artificially increase their dealer assistant count.
Fix badge label for new attendees

ribbon_and_or_badge doesn't output anything for new attendees, so this
defaults just to the badge type label instead.
Add table extra opts

Adds a new field to the Groups database so dealers can select extra
options. Also updates the forms to comply and price the options out. A
bit rough.
Change dealer ribbons to dealer assistants

Adds an AnthroCon-specific mod that only assigns a Dealer ribbon to the
group leader of a dealer group. The others are considered dealer
assistants.
Hide phone opt-out for dealers

Dealers aren't allowed to opt out of a phone number, so the checkbox to
do so is now hidden for them.
Text changes

Modifies the dealer page so that the text reflects AnthroCon's needs.
Improve table_extras calculation

The system now supports any table_extras added via configuration.
Merge pull request #832 from magfest/dealer_changes

AC Dealer changes