Move translators credits list to a wiki page

* List as per Iedc78728156f04b16109140db485492ba7693f14
  (to be occasionally updated manually on wiki with automatic authors
  lists from the files as exported by the Translate extension)
* Link it from Special:Version
* Make protocol consistent in the different parts of the sentence

Change-Id: I3bb53d4c184173b5362f5036764fb38d8f07d178