Fsroot flag added

This kind of piggybacks on my previous PR, so I'm happy to close that and just do this one if you prefer.  I noticed on my nodes that they couldn't find their workspace after the init script updates, so I added this to allow folks to specify it if the defaults didn't work as expected.

I don't have a Debian/Ubuntu box to test with so I'm not 100% sure what to expect there :)