First version of Japanese translation. Thanks to Naoto Nakashima.

Squashed commit of the following:

commit d8b311859b1f4f36b94e0411d7d6a5431486c8e4
Author: Martin Gruner <martin.gruner@otrs.com>
Date:   Tue Jul 22 16:37:33 2014 +0200

    First version of Japanese translation, thanks to Naoto Nakashima.

commit 22aad19c18ba7a904d6aaf3dd63e50e3061be035
Merge: 9d1f18c 17284be
Author: Martin Gruner <martin.gruner@otrs.com>
Date:   Tue Jul 22 15:02:02 2014 +0200

    Merge branch 'rel-3_3' into feature-japanese-mg-33

commit 9d1f18c0046d9a0f667f7172389c2401898bf5b7
Author: Martin Gruner <martin.gruner@otrs.com>
Date:   Mon Jun 23 22:06:06 2014 +0200

    WIP

commit 9b5322b0dde943e5d87b8efbc188be987aa3a604
Author: Martin Gruner <martin.gruner@otrs.com>
Date:   Mon Jun 23 17:21:05 2014 +0200

    WIP on including japanese translation.