Feature: multi language

[mahito1594]

Dear @vividvilla

Thank you for this great theme! But, I think, it is more convenient that the theme can deal with multi language page. Therefore, I modified following:

Modify hyperlink of title

When click the site title, we can go to the home of present language.

Add hyperlink to its translations

When the present article has translations, the link to them will appear on the same line with the menu.

All changes work well on my web site, it contains Japanese and English pages (now, it has only home and about page...). I have just started to use Hugo, and not being familiar with HTML/CSS. If this PR is silly, please discard.

Thanks,