Vendoring gems
Adding local search for vendored gems

Using https://github.com/github/pages.github.com/blob/gh-pages/script/bootstrap#L18 as a reference
Must use GitHub version of Ruby for internal CI
Merge branch 'vendoring-gems' of github.com:github/training-materials into vendoring-gems
Merge pull request #5 from github/vendoring-gems

Vendoring gems