Top words insight

Reading this insight generated from live data, we see there are some cases (like this one here) where the wording is a bit awkward, especially since "mention" has a special meaning on Twitter. Let's update this line to "%username said the word "%words" more than any other on %network this month."

![amp](https://cloud.githubusercontent.com/assets/60632/4884511/70fbfa42-636c-11e4-87cd-e4a0ccd3b1a6.png)