Update japanese translation

[TakehideMorimoto]

I made a Japanese translate here.

[flaix]

Hi! This is awesome!

I found some issues in your files, so you may want to go over them again and make sure you have no duplicate keys, no incorrect keys and no empty definitions.

What is more, though, is a technical issue. Your changes are based on a rather old commit and then merged into your master. This way I cannot merge them. A merge request should always come from a separate branch, not from master. (And only contain the changes for one feature/topic.) So can you create a new branch on top of the current master of gitblit/gitblit and cherry-pick only the one commit 17da704 onto it? I do think that you will probably have to create a new merge request for it.

If you don't know how to do that, that is also not a problem. In that case you can also add a new commit to fix the issues and I will then create new commit from your commits for you.

Please be advised that several issues with language files have been fixed (see PR #1380), which also touched the Japanese properties file.

In any case, thank you very much for taking the time and improving the Japanase translation!

[TakehideMorimoto]

Sorry. I will go over some issues that you point out, and make sure keys.
And I create new branch and new merge request another day.

[flaix]

I have fixed the submission and added it under a new commit to the main branch.
Closing this as done.