Basically, with the code until now, if an user was trying to view
a binary file in the UI, it was then prompted to download the file
(as pagure doesn't know how to display binary file), but the file
the users were downloading wasn't the raw file but rather the html
page that would contain the file.
Not ideal.

So with this commit we're now just saying: if the file is binary and
we can't render it, just return the raw file to the user and let
them deal with it.

Fixes https://pagure.io/pagure/issue/4907

Signed-off-by: Pierre-Yves Chibon pingou@pingoured.fr