Asset colocation for files without an extension

Hi!

In versions 0.15.3 to 0.17.0 Zola would colocate files without an extension. I serve files without an extension on my website fairly frequently and would prefer to avoid renaming them if possible (rehosting challenge binaries for CTF writeups). I would like to be able to configure and disable that behavior. I'm happy to fix and MR this but wanted to chat about design first.

Thanks!