Merge branch 'oauth-require-public-email' into 'master'

Oauth Require Public Email

Does not fix #976 yet, but will reduce the amount of users getting 422 immensly.

app/views/devise/sessions/_oauth_providers.html.haml

@@ -2,10 +2,12 @@
 - if providers.present?
   %hr
   %div{:'data-no-turbolink' => 'data-no-turbolink'}
-    %span Sign in with:  
+    %span Sign in with*:  
     - providers.each do |provider|
       %span
         - if default_providers.include?(provider)
           = link_to authbutton(provider, 32), omniauth_authorize_path(resource_name, provider)
         - else
           = link_to provider.to_s.titleize, omniauth_authorize_path(resource_name, provider), class: "btn"
+    %br
+    %small * Make sure your email address is public