Functionality for discounts:

- Added the base classes and a lot of logic for how discounting a vendor will work on the back-end.
Now just need to tie it into a form and finalize it in the morning.

Note to self: Great deal of headaches will come when I want to allow for global discounts based on
all events for 1 category.  To alleviate this make sure I set a VendorPricingTier model not tied into
active record so that we can do quick (KEY: QUICK) on a hash table for some of the more important info.
A library file is fine for now based on all testing, but for later usage abstract this out into a global class.