adds omniauth basic authentication process with Twitter, including an intermediate step to ask the user for her email if not provided by the OAuth provider - Twitter, for instance

app/views/users/registrations/finish_signup.html.erb

@@ -0,0 +1,13 @@
+<div class="auth row">
+  <div class="small-12 medium-8 large-5 column small-centered">
+    <div class="panel">
+      <h1><%= t('omniauth.finish_signup.title') %></h1>
+
+      <%= form_for current_user, as: :user, url: do_finish_signup_path, html: { role: 'form'} do |f| %>
+        <%= render 'shared/errors', resource: current_user %>
+        <%= f.email_field :email, placeholder: t("devise_views.users.registrations.new.email_label"), value: nil %>
+        <%= f.submit t("devise_views.users.registrations.new.submit"), class: 'button radius' %>
+      <% end %>
+    </div>
+  </div>
+</div>

app/views/users/registrations/new.html.erb

@@ -2,6 +2,9 @@
   <div class="small-12 medium-8 large-5 column small-centered">
     <div class="panel">
       <h2><%= t("devise_views.users.registrations.new.title") %></h2>
+
+      <%= render 'devise/omniauth_form' %>
+
       <%= form_for(resource, as: resource_name, url: registration_path(resource_name)) do |f| %>
         <%= render 'shared/errors', resource: resource %>