Update git submodules
- Update skins/MonoBook from branch 'REL1_39' to 13c2031aed8cbf3983fa5fac377bf067a6da9153
- Localisation updates from https://translatewiki.net.
Change-Id: Id71a51698308edb5d9d074518332e8ff76dc4ece
- Localisation updates from https://translatewiki.net.