setup: update utils.sh
setup: update utils.sh

Use return 0 instead of exit 0, because exit 0 will end whole process.

Add new function `insert_line` in setup/utils.sh:
  The setup script can use this function to update configure file, such as
  ~/.bashrc. Therefore, we don't need to override the whole file. It's
  easy to control what we install.

fhfuwei/dotfiles,0x04C2/dotfiles