Merge pull request #430 from masterkain/fix_rails_respond_with

Make Rails' respond_with play nice with to_json.

lib/fog/core/collection.rb

@@ -115,9 +115,9 @@ module Fog
       Formatador.display_table(self.map {|instance| instance.attributes}, attributes)
     end
 
-    def to_json
+    def to_json(options = {})
       require 'json'
-      self.map {|member| member.attributes}.to_json
+      self.map {|member| member.attributes}.to_json(options)
     end
 
     private

lib/fog/core/model.rb

@@ -37,9 +37,9 @@ module Fog
       self
     end
 
-    def to_json
+    def to_json(options = {})
       require 'json'
-      attributes.to_json
+      attributes.to_json(options)
     end
 
     def wait_for(timeout=Fog.timeout, interval=1, &block)