Re-enable use of BAR_PATRON and UNBAR_PATRON perms

Re-enable use of BAR_PATRON and UNBAR_PATRON perms

If you aren't allowed to bar/unbar at the patron's home library then:

1 - Disable the checkbox as appropriate
2 - Disallow on the backend too

The frontend only checks on page load. The backend checks the old patron on
update and the new patron on create.

This does not stop "change home library to me, bar/unbar, change back" if
otherwise able to change the patron's home library.

Signed-off-by: Thomas Berezansky <tsbere@mvlc.org>
Signed-off-by: Bill Erickson <berick@esilibrary.com>