Joboptions attachment not downloadable

[octosquid]

1. open ftp://pubftp.computer.org/press/outgoing/proceedings/Acrobat_Distiller_Job_Options_Files/InstallingSettings-V32Add-Win.pdf
2. open attachment overview
3. click onto IEEE-PDF-Acrobat7-29Nov05.joboptions
4. nothing happens, no download offered

I admit, a joboptions file is pretty useless, downloading makes no sense. However, when there is the entry, people expect to be able to download.
I don't know, perhaps pdf.js should hide joboption attachments instead.

[yurydelendik]

It happens that firefox does not know what to suggest for '.joboptions' file. Changing attachments mime type to 'application/octet-stream` at https://github.com/mozilla/pdf.js/blob/master/extensions/firefox/content/PdfStreamConverter.jsm#L277 will kinda fix that, but breaks know types. I'm okay will regressing the latter in favor of this bug.