Update Japanese namespace names / 日本語の名前空間の更新

Hi all!
I'm aokomoriuta, a Japanese translator of MediaWiki in translatewiki.net.

According to discussion[1] in translatewiki.net,
we dicided change Japanese namespace names of MediaWiki and it has been changed in r66497[2].
You can get summary of this change at translatewiki.net/Support[3]

<To all users>
Some problem which occured when "画像"(Image) namespace changed to "ファイル"(File) might be
caused by this.
For example if you hardcode the namespace names in your wiki, it doesn't work yet.
Check it and do not use hardcoded names no more.
 {{#switch:{{NAMESPACE}}|ノート = foo|Category = bar|...}}
  -> {{#switch:{{NAMESPACE}}|{{ns:Talk}} = foo|{{ns:Category}} = bar|...}}

<To all system admins>
If you don't want to accept this change, do not update "/languages/messages/MessagesJa.php",
or edit (revert) this messages manually.

<To all this list subscriber>
We're looking for new Japanese translator in translatewiki.net at all times!
Vist http://translatewiki.net/ and our Portal[3], and join us!

----- Japanese translation -----
こんにちは。
translatewiki.netでMediaWikiのローカライズをしています、青子守歌といいます。

translatewiki.netでの議論[1]の結果、MediaWikiの名前空間名を修正することが決定され、r66497[2]で修正されました。
修正の概要はtranslatewiki.net/Support[3]で見ることが出来ます。