Always update from vundle

Previously, the after-up hook would only do a `:BundleInstall` when
installing vundle for the first time. This is inconsistent with the
pre-rcm process, and also less convenient.
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.
Initialise rvm, if it's installed