We'll start off simply enough by modifying our templates. We're going to add links to login with Google in both our login page and our new user account page. We'll start in lib/vocial_web/templates/session/new.html.eex:
<br /> <%= link "Login with Google", to: "/auth/google" %>
And then modify our account creation page as well with a very similar link in lib/vocial_web/templates/user/new.html.eex:
<br /><%= link "Sign Up with Google", to: "/auth/google" %>
Finally, in the session controller (lib/vocial_web/controllers/session_controller.ex), we'll need to add a build_user_from_auth/1 that accounts for Google being the provider instead of Twitter. Google doesn't give us back a username, ...
