Added japanese translation.

src/Locales/ja_JP.php

@@ -0,0 +1,42 @@
+<?php
+// locale: Japanese ( ja-jp )
+// author: Takumi https://github.com/takumi-dev
+return array(
+    "months"        => explode('_', '1月_2月_3月_4月_5月_6月_7月_8月_9月_10月_11月_12月'),
+    "monthsShort"   => explode('_', '1月_2月_3月_4月_5月_6月_7月_8月_9月_10月_11月_12月'),
+    "weekdays"      => explode('_', '月曜日_火曜日_水曜日_木曜日_金曜日_土曜日_日曜日'),
+    "weekdaysShort" => explode('_', '月_火_水_木_金_土_日'),
+    "calendar"      => array(
+        "sameDay"  => '[今日]',
+        "nextDay"  => '[明日]',
+        "lastDay"  => '[昨日]',
+        "lastWeek" => '[先週]l',
+        "sameElse" => 'l',
+        "withTime" => 'H時i分',
+        "default"  => 'Y年m月d日',
+    ),
+    "relativeTime"  => array(
+        "future" => '%s後',
+        "past"   => '%s前',
+        "s"      => '数秒',
+        "m"      => '1分',
+        "mm"     => '%d分',
+        "h"      => '1時間',
+        "hh"     => '%d時間',
+        "d"      => '1日',
+        "dd"     => '%d日',
+        "M"      => '1ヶ月',
+        "MM"     => '%dヶ月',
+        "y"      => '1年',
+        "yy"     => '%d年',
+    ),
+    "ordinal"       => function ($number)
+    {
+        $prefix = '第';
+        return $prefix.$number;
+    },
+    "week"          => array(
+        "dow" => 1, // Monday is the first day of the week.
+        "doy" => 4  // The week that contains Jan 4th is the first week of the year.
+    ),
+);