Latest commit ce08d7a May 2, 2017 @trammel trammel Replaced render :text 404 with :plain in omniauth
Rails 5.1 has deprecated render :text, and HEAD requests on the
omniauth callbacks passthru method is causing errors because the render
:text is non-existant, and there's no template to fall back to.

Replacing :text with :plain, adds a content-type type of text/plain and
also returns the previous message.

render :plain was supported back in rails 4.1.0
http://api.rubyonrails.org/v4.1.0/classes/ActionView/Helpers/RenderingHelper.html#method-i-render