Update git submodules
- Update skins/MonoBook from branch 'REL1_39' to 7913ee79d4a1ca3bab8d1689cf5c8aaed67c4c3b
- Localisation updates from https://translatewiki.net.
Change-Id: Id21d86f9af8f76b6baeaf449f4001ced51857f8f
- Localisation updates from https://translatewiki.net.