Add Japanese translation of scala-for-java-programmers

[exoego]

Add Japanese translations of Scala for Java Programmers

[exoego]

It looks like that ja for japanese in a phrase "scala-for-javaprogrammers" is removed somehow and makes the link broken...

- ./_site/tutorials/scala-for-java-programmers.html
  *  internally linking to /ja/tutorials/scala-for-va-programmers.html, which does not exist (line 1110)
<a href="/ja/tutorials/scala-for-va-programmers.html" class="lang">日本語</a>

This accidental removal of ja happens only in the original (English) page.

EDIT: It is fixed in a57151e

[exoego]

@eed3si9n
Could you kindly review this?

[eed3si9n]

Of course :)