New Dictionary Words Insight

Takes a list of date/word/insight text combos, looks for the user
having ever said that word in the past, and generates a new insight.

Closes #2057
New dictionary word counts insight: Space out Facebook and Twitter schedule
Insight Terms::swapInSecondPerson: Add support for %username was
Activity spike new-style headlines
Follow count visualizer new-style headlines
Email subject lines: Use insight headlines for 20% of users
Big reshare: new style headlines
Twitter Crawler: Update friends' profiles every day instead of every other day