FEATURE: verbose SSO logging

By enabling the site setting verbose_sso_logging
you can log information every time a user tries initiates SSO
and during SSO failures

lib/single_sign_on.rb

@@ -55,6 +55,12 @@ class SingleSignOn
     sso
   end
 
+  def diagnostics
+    SingleSignOn::ACCESSORS.map do |a|
+      "#{a}: #{sso.send(a)}"
+    end.join("\n")
+  end
+
   def sso_secret
     @sso_secret || self.class.sso_secret
   end