Link user's bday with calendar event

[ryanhowdy]

Currently the calendar entry for a user's bday is not linked anyway to the actual bday for the user.

We need a way to link them together, whenever you update one, it updates the other.

Need to add code to the upgrade script that will remove all existing birthdays? We might delete birthdays for people not registered.

Possible solutions:

1. Make the actual calendar event read only, and only allow it to be updated when the user changes their bday in their profile. Probably need a way to link them together either in the calendar or user table.

1. Remove the calendar event all together and update the calendar to search the user's bday from the user's table.