Improve ajax call to build page url slug

* Disable form submission until ajax request has finished
* Don't do ajax request if page name is the same as the previous ajax
  request
* Take in account the ajax response (success of fail) only if it's for the
  last ajax request.
Fix backup messages

The correct way to signal errors in controllers is $this->error->add()
and not $this->set('error', array(...)).

Furthermore the redirect after a successful restoration should be
restoration_successful and not backup_successful
Fix missing/wrong translations
Merge pull request #1386 from mlocati/fix-backup-error-messages

Fix backup messages
add jHandle support
Merge pull request #1388 from Remo/job-handle

add jHandle support
Merge pull request #1340 from mlocati/fix-slug-ajax-build

Improve ajax call to build page url slug
Made the field bigger for job responses so we can have really long responses (or errors)
Merge pull request #1394 from Mnkras/jobs-status-bigger

Made the field bigger for job responses so we can have really long respo...