Have a different global `.gitignore_global` file as the global `.gitignore` file (by default `git` would just grab the `.gitignore` file in the user home directory) for the dotfiles repo's `.gitignore` to work.
Remove `.zshrc` file as changing to use Prezto, it will symlink a file to it.
Add some helper files to configure OS X, install some Homebrew formulae and `brew cask` applications.