Comment 5 for bug 991033

Created attachment 617270
Fix offline handling in _uploaderCallback

I noticed that the try/catch hadn't been added to _uploaderCallback() as part of the offline error handling, so I've added that. This seems to have all of David's changes, so this is the patch to review.

As with the last patch, it still needs the referral codes in some of the links, but that shouldn't prevent the code itself from being reviewed.