EOY email styling

n.b. this only updates the compiled template - source email template in /extras is not updated, so recompiling from source will overwrite these edits.
EOY landing page design
Add ?yearend=1 to the querystring to see the landing page
EOY landing page backend + design tweaks

Implement tomorrow's teaser
EOY insight design: Fix header image
Issue #2133: EOY Most favliked post of the year
Issue #2128: EOY Biggest Fans insight
Issue #2129: EOY Most talkative day
Issue #2154: EOY All About You insight
Issue #2130: EOY Most popular pic
Issue #2131: EOY Exclamation Count
Issue #2132: EOY F-bomb count
Staging: Test EOY Most Favliked
Staging: Test EOY All About You
Staging: Test EOY Most Talkative Day