Stats: Top Posts module displays "Home Page / Archive" even when Home Page is explicitly set

[hoverduck]

When the home page is explicitly set to a page, views for the homepage are counted toward that page, and not "Home Page / Archive". We should adjust the label for "Home Page / Archive" to just read "Archive" in these cases.

Whatever update we make here should flow down on to the summary page as well.

Some discussion (p1431718854000281-slack-data) about where an "archive"-only entry would link, and whether it should link anywhere at all. I'm in favor of either not linking it, and having a tooltip next to the row that explains it that archives are author, tag, and category pages, or of linking it to a help article explaining that.

Just noting that I came across some confusion about these labels (for a site with a static front page) in the forums here:
http://en.forums.wordpress.com/topic/why-does-home-pagearchives-show-up-in-my-stats

[timmyc]

dupe of #210