Update git submodules
- Update skins/MonoBook from branch 'REL1_39' to 685d74abb127cbccf8ab179194b4ff8e8296a71f
- Localisation updates from https://translatewiki.net.
Change-Id: Ied0a717a4b8a40a849416c7cd0fa53852655f60b
- Localisation updates from https://translatewiki.net.