More extension points for login buttons, used by OAuth2 plugin

lib/plugin/auth_provider.rb

@@ -1,9 +1,25 @@
 class Plugin::AuthProvider
-  attr_accessor :glyph, :background_color, :title,
-                :message, :frame_width, :frame_height, :authenticator
+
+  def self.auth_attributes
+    [:glyph, :background_color, :title, :message, :frame_width, :frame_height, :authenticator,
+     :title_setting, :enabled_setting]
+  end
+
+  attr_accessor(*auth_attributes)
 
   def name
     authenticator.name
   end
 
+  def to_json
+    result = {name: name}
+    result['titleOverride'] = title if title
+    result['titleSetting'] = title_setting if title_setting
+    result['enabledSetting'] = enabled_setting if enabled_setting
+    result['messageOverride'] = message if message
+    result['frameWidth'] = frame_width if frame_width
+    result['frameHeight'] = frame_height if frame_height
+    result.to_json
+  end
+
 end