Add a japanese translation file

lib/paperclip/locales/ja.yml

+ja:
+  errors:
+    messages:
+      in_between: "の容量は%{min}以上%{max}以下にしてください。"
+      spoofed_media_type: "の拡張子と内容が一致していません。"
+
+  number:
+    human:
+      storage_units:
+        format: "%n %u"
+        units:
+          byte:
+            one:   "Byte"
+            other: "Bytes"
+          kb: "KB"
+          mb: "MB"
+          gb: "GB"
+          tb: "TB"