COPPA 6.x upgrades

Needing to use the COPPA module in a Drupal 6.x site, I made the following changes to fix a variety of bugs and glitches:

• Added theme handlers to all forms, so theme_* functions will work.
• Fixed 5.x style form arguments, eg: my_form($form_id, $edit)
• Changed many $edit variables to $form, since this is what they are in 6.x
• Removed unnecessary use of unserialize after variable_(get|set)
• Remove extraneous coppa_admin_settings_submit() function, not needed in 6.x
• Fixed missing {table_name} wrappers on some SQL queries.
• Added a permissions string for limiting who sees the "Sign COPPA compliance" menu item
• Changed all true and false to TRUE and FALSE. OK so I'm being a bit picky ;-)

Please let me know if you see any issues with the patch!