do not prompt for github username if not default
do not prompt for github username if not default

atomantic/dotfiles,naxhh/dotfiles,5112n4/dotfiles-atomantic,kmees/dotfiles,priyavadan/dotfiles,naxhh/dotfiles,naxhh/dotfiles,kmees/dotfiles,priyavadan/dotfiles,atomantic/dotfiles,rubybrowncoat/dotfiles,atomantic/dotfiles,rubybrowncoat/dotfiles,5112n4/dotfiles-atomantic