Implemented discount feature

When a discount is created it has at most one price entry for each conference item that has been declared
If an itinerary has a a discount key matching a discount in the db then when conference items are priced the discounted prices will be used instead of the regular prices

Extras
All users must fill out contact info for controllers which use the check_contact_info filter
Admin panel displays the conference year on relevant pages
Discount Bug Fixes
primary keys for associations fixed
redirects to the discounts index after create/update
line items can have a price greater than or equal to zero
Payment Disclaimer
Emergency contact info for users

Also refactored labels to display differently
New login page

Also modified the contact us form so a jquery telephone formatter would attach to the new telephone field
Hide validation errors on sign up