Merge #626: Translations: update old unmerged translations to pass new tests

e1475de Translations: update old commits to pass new tests (David A. Harding)
c33e86e Add japanese translation for 0.16.0 (azuchi)
7c4a105 Add japanese translation for segwit benefits (azuchi)

Pull request description:

  Closes #511
  Closes #516

  This rebases the above PRs and makes some minor tweaks to the content so that they'll merge cleanly.

Tree-SHA512: ebf1cb491a2fe119799706df0d3861c11f990eff6b4d36d33c7e25c8b0b36ecdc5a19d77e8d674210f17f2527996aab7178224ed1a249900ac7159a0aeb18bc7

Author: harding

_data/navigation.yml

@@ -303,7 +303,7 @@ ja:
         url: "/en/2015/12/23/capacity-increases-faq/"
       segwit-faq:
         title: "Segwit"
-        url: "/en/2016/01/26/segwit-benefits/"
+        url: "/ja/2016/01/26/segwit-benefits/"
       segwit-dev:
         title: "Segwit開発ガイド"
         url: "/ja/segwit_wallet_dev/"