Sublime syntax highlighting

For too long we've lived with angry pink highlighting around D3 code.

![screen shot 2014-06-03 at 1 12 01 pm](https://cloud.githubusercontent.com/assets/3344958/3165988/93b701d2-eb5b-11e3-8a09-a51bad81325f.png)

Lame. This commit makes sublime recognize things in `typings/`, so it stops complaining and starts giving suggestions.

![screen shot 2014-06-03 at 1 15 09 pm](https://cloud.githubusercontent.com/assets/3344958/3166018/f17678fc-eb5b-11e3-980c-b9fee38c7c68.png)

To get this to work, run `grunt sublime`, then quit sublime and re-open.