bringing chart factories and chartutil (plus Watson) into tideline from blip

@nicolashery Do you want to look at the basic idea here? This isn't finished yet (don't merge), but the organization is how I think I want it.

Probably you want to look at the Makefile to see how I'm bundling things, but the basic idea is:
- `plugins/blip/` contains the chart factories
- `plugins/data/` contains Watson and what was `chartutil.js` in blip and will now be `tideline.preprocess`