Add support for Slackware

[Chibani]

I would like to see ash working on Slackware.

[Reza]

I made some progress on it a few months ago, but it's been quite some time since I installed it (and have not really used it in any meaningful way). Would you be able to take a crack at it?

[Chibani]

I'm going to do my best to address this in the future. Slackware is a suitable option if the profile is functioning effectively.