Update Giant Robots blog post URLs in README
Only try to install vundle if it's not installed

Prevents error on re-running ./install.sh:

    fatal: destination path '~/.vim/bundle/vundle' already exists and is
    not an empty directory.

https://github.com/thoughtbot/dotfiles/issues/195
Add Git credentials.
Initialise rbenv on startup.
Add Homebrew directory to PATH.
Move personal details to local files.
Add Github Enterprise settings.
Add Github CLI.
Look for GitHub Enterprise settings.