Drop the use of nohup on OSX for tmux compatibility
Drop the use of nohup on OSX for tmux compatibility

Apparently `nohup` is not needed in OSX, and using it has the side
that it may break under tmux with the error

  nohup: can't detach from console: No such file or directory

For now, this commit only drops the use of `nohup` in OSX. But it
*may* not be necessary under other similar platforms.

FrankSansC/oh-my-zsh,FrankSansC/oh-my-zsh,FrankSansC/oh-my-zsh,FrankSansC/oh-my-zsh