Change homepage blog post

Updates the homepage featured blog post to be less stale (previously Fellowship Application Stats, up since October 16). This makes the featured post Jen's Thanksgiving look back.

Some tongue-in-cheek-ish humor in the header (Giving Thanks For America vs. Blogging For America) and creative excerpting to get interesting stuff out on the homepage.

/cc @Jaime-Alexis batter up for you to merge.