Move a locale files for ActiveRecord (#2461)

ref #2162 and fix #2460

diff --git a/config/activerecord.en.yml b/config/locales/activerecord.en.yml
similarity index 100%
rename from config/activerecord.en.yml
rename to config/locales/activerecord.en.yml

diff --git a/config/activerecord.ja.yml b/config/locales/activerecord.ja.yml
similarity index 100%
rename from config/activerecord.ja.yml
rename to config/locales/activerecord.ja.yml