Add shebang and use double quotes

I noticed that in some rows, you are using double quotes and in some you don't. In row 80, there should be double quotes as well, but I can not test it right now. I ran it through shellcheck and there are still some warnings left. Also, I added shebang.

This PR is going to fix Oct 10 12:52:38 turris ATLAS[24702]: /usr/libexec/atlas-probe-scripts/bin/ATLAS: /usr/libexec/atlas-probe-scripts/bin/arch/turris-sw-probe/turris-ATLAS.sh: line 67: hostname: not found