Add button to update expire date field

Add button to update expire date field

When updating/renewing a patron (expired or not), it would be
convenient to have a means of populating the expire date field with
a value of perm_interval + today. Currently, staff are required to
manually enter a date, or could toggle the profile from one profile
then back to the desired profile, but this is not ideal.

This commit adds a new button next to the expire date, which when
activated will re-calculate the date based on the current profile's
perm_interval and today's date.

This is similar to how the expire date is populated when creating a
new user, or when changing the profile group. A button is used here
so that the updating of the expire date is an intentional process,
not one that happens upon any edit.

Signed-off-by: Jeff Godin <jgodin@tadl.org>