Nutrition IA

This is still a WIP, but opening the PR because it's working and I could use input about how to clean up some of the triggering/relevancy stuff. I'm sure there will still need to be UI tweaks as well.

![screen shot 2014-10-19 at 5 36 54 pm](https://cloud.githubusercontent.com/assets/126358/4694833/2a412a18-57d8-11e4-862e-7fbc52799cc1.png)
![screen shot 2014-10-19 at 5 37 59 pm](https://cloud.githubusercontent.com/assets/126358/4694837/3b0596ae-57d8-11e4-8f3b-bc44a429adcb.png)

@russellholt @jagtalon @chrismorast 
Personally, I'd probably want better test coverage around the question formats such as:
* "how much protein in tuna"
* "how many calories in a banana?"