Check permissions in RecentChanges & Contributions feeds

Log & CheckUser are less easy to implement right away, and there's
an upcoming ticket that will likely make that implementation easier.
https://trello.com/c/S10KfqBm/62-8-history-watchlist-rc-and-contribs-changes

I've added some @todo's in the code, so we can pick Log & CheckUser
back up later. I'll file a bug to keep track.

Change-Id: I96cf15fce23fffad6e35a779ac2bd94b1208a680