0.9.6: Decided to go back to fs.cp

After literally sleeping on it, I decided to switch fs.write back to fs.cp. I originally wasn't happy that "fs.cp()" didn't really work like the os cp, because src was relative to the playbook. But I decided I was ok with that, giving an escape hatch of specifying absolute paths, and possibly adding a flag to "use_cwd" or similar if that functionality is desired.