[Note] Upgrade Ralis to 4.2.9
bundle update rails responders
兩個要一起更新，不然會發生錯誤
Bundler could not find compatible versions for gem "actionpack":
In Gemfile:
rails (~> 4.1.14) was resolved to 4.1.15, which depends on
actionpack (= 4.1.15)
responders (= 2.4.0) was resolved to 2.4.0, which depends on
actionpack (< 5.3, >= 4.2.0)
bundle update 完成後再執行
rake rails:update