Add headers to home template

[jayhesselberth]

Fixes #918

[jayhesselberth]

@hadley Before merging, can you check the content-article.html template to see if we need to copy anything else into the content-home.html template?

I'm not sure what this does at the bottom of the article template:

$for(include-after)$
$include-after$
$endfor$

[hadley]

I don't think that block is currently used, but probably should be included for the sake of completeness.