Remove "Latest activity" column #21
Description
Having both "Latest email" and "Latest activity" is on the homepage is kind of useless. The "Latest activity" often is simply the date when a patch was moved to the next commitfest, so it's content is rather useless in general. If we improve the commitfest app to contain more useful info (e.g. by implementing #19) it might become more useful to have this timestamp though. For now it seems fine to remove though, and once we implement #10 we can add his back as an option.