Flexible contact matching

[emagnuson]

It would be really nice if the user could specify the fields used
for matching a SF contact to an EB attendee/payer. So for example,
let's say that a user wants to match eventbrite contacts to contacts
in SF based on first, last, and address line 1. Or, let's say they
want to match on any of the NPSP email address fields as opposed to
just the standard SF email field.