Bug 7162; Factorize code for order cancellation (QA fixes)

Bug 7162; Factorize code for order cancellation (QA fixes)

* Remove tab characters in acqui/addorder.pl
* Remove FIXME in acqui/cancelorder.pl
* Fix typos: "canceled" -> "cancelled", "occured" -> "occurred"
* Replace "Click here" link by "OK"
* Add a column to aqorders to store cancellation reason instead of
  having it in aqorders.notes, to avoid having untranslatable strings in
    database

Signed-off-by: Paola Rossi <paola.rossi@cineca.it>
Signed-off-by: Tomas Cohen Arazi <tomascohen@gmail.com>