just found out: call the following URL in your browser: http://<your server>/Orion/Admin/AdvancedConfiguration/Global.aspx
Which leads you to advanced configuration. There you'll find FirmwareRepositorySearchPattern, where *.bin is already configured.
It looks as if you could enter more file extensions there, but it's not mentioned what the delimiter is, if more than one entry exists. So far I've tested with
but none of these seems to work. Currently I'm fed up and have stopped trying, because I have work to do.
If you find the solution I'd be only too happy to know
The only work around i can see at the moment is to use a double extension .tar.bin. I have submitted a feature request for this, did you ever find the non-default setting?