clamav 0.98.5

* Version bump. 
* Fixed head.
* New recommend dependency *(It’s actually an old recommended dependency that we haven’t been building).* 
* Moves the sysconf dir to a directory inside HOMEBREW_PREFIX/etc to make it a little tidier.
* Adds some caveats to explain clamav’s confusing error messages on initial run.
* Adds a test.
Yeh, I guess what we've done in some other cases is just copy the sample into the default location so there's something working. If that's not an option here I think it's cool to just leave it and say that people will need to edit (but omit the stuff about `.sample` as I think it's probably more confusing than helpful)