Feature: requestId-based row grouping

This adds proper row grouping by request ID. Currently, tv merges all responses for a particular request together and displays a row with the aggregate data. This keeps the responses separate and allows the user to visually group them together with a toggle. Turning on grouping re-sorts the table to pull groups together ordered by the timestamp of the first response from that group.

GIF:

![tv-grouping](https://f.cloud.github.com/assets/808159/1936723/6963b06c-7f11-11e3-9dcf-65ace5378039.gif)

Screenshots:

![screen shot 2014-01-16 at 4 44 34 pm](https://f.cloud.github.com/assets/808159/1936725/6f361cfa-7f11-11e3-94f0-61abce1b24b8.png)
![screen shot 2014-01-16 at 4 44 42 pm](https://f.cloud.github.com/assets/808159/1936727/723f9700-7f11-11e3-8816-ac14c4afa28b.png)

/cc @hueniverse @wpreul @thegoleffect