Updates the list of shares.
The first array is a list of people that are to be added to the calendar.
Every element in the add array has the following properties:
* href - A url. Usually a mailto: address
* commonName - Usually a first and last name, or false
* summary - A description of the share, can also be false
* readOnly - A boolean value
Every element in the remove array is just the address string.
@param array add @param array remove @return void
def update_shares(add, remove)
end