(bug 48308) Change namespace settings for ukwikisource

This patch follows up I0b05d2f and adds necessary English namespace
aliases for the 'Author' and 'Author_talk' namespaces. It also adds
the remaining settings for $wgProofreadPageNamespaceIds.

Bug: 48308
Change-Id: I7cd012d4643f388c9ebc300f2e976a3977a03de1