Build script

## Implements a basic grunt task to generate index.htm

- Watches views/**.jade and structure.json for changes
- Pulls the interludes defined in structure.json
- Pulls the data in data/dpic.json, groups it by year, which become sections
- Interlaces the interludes into the year sections based on the year (after) defined in structure.json
- Does not yet completely faithfully recreate the DOM structure from the sketches repo, but getting there should be as simple as tweaking the jade templates
- Includes the essays in data/essays matched to executions based on the FirstLast-year identifier

*Note:* I chose not to include the names list in structure, since it seemed redundant with the presence of the essay in data/essays (don't feel strongly about this, but wanted to make it as simple as possible to add an essay).

*Also note:* This totally breaks the current build (I think that's ok, it was pretty broken already, and let's start over).

*TODO:* Still want to add stronger safety checking (every defined interlude gets included in the dom, every essay gets matched with an execution). Also haven't sorted out the problem of how to initialize the interludes (unless they initialize themselves, which I feel medium about).