No more Unique Emails Required

If using the Recommended Beta version, registrants no longer need to input unique email addresses. This caused a major issue since we import our registrations into a system each morning and noticed that 2 orders had someone registering more than 6 people under the same email address. Email addresses are naturally the unique identifier in any CRM or like-system, which is why this should always be enabled.

There are cases where people have stated that a parent may register kids, which wouldn't have their own email addresses, so if this is the case, include an optional check to disable unique emails - but don't have it disabled by default