Cosmetic fixes in the API browser HTML.

I had a quick go at this, just gathering some feedback, I can split into two PR if needed.

- The tooltip issue is documented in the Bootstrap docs as "Tooltips & popovers in button groups require special setting":

![screen shot 2014-12-03 at 5 10 33 pm](https://cloud.githubusercontent.com/assets/36160/5279107/bae45e6a-7b13-11e4-8018-cc3888cd1149.png)

- I naively assumed that the Bootstrap 2.x markup was simply forgotten but feel free to disregard if it was left there to remain compatible with user's overridden forms / templates:

![screen shot 2014-12-03 at 5 11 22 pm](https://cloud.githubusercontent.com/assets/36160/5279122/f06f2bc8-7b13-11e4-9c14-0172c53f9ed8.png)
![screen shot 2014-12-03 at 5 43 25 pm](https://cloud.githubusercontent.com/assets/36160/5279133/0a77cee4-7b14-11e4-85d1-319efef94990.png)