Add the B/C i18n shim

I mistakenly was under the impression that CentralNotice was only used by
WMF wikis. Adam Wight pointed this out. This is a follow-up to
06df9c0de7d5a309466f6eb73b5c48a9092be0e2.

Change-Id: Ie6a4a95fdac6f71e55cc7bf1cccf0eb7565b9759