Add component.json

TJ’s [Component](https://github.com/component/component/wiki/F.A.Q) is a great tool to build standalone JS from npm package (to work in browser or any non-node environments).

For example, [Autoprefixer](https://github.com/ai/autoprefixer) uses Component to pack all it files and npm dependencies in one `autoprefixer.js` and run it in `autoprefixer-rails` (Autoprefixer integration to Rails/Ruby). It is necessary, because JS runtime in Ruby doesn’t work with file system and doesn’t have `require()`.

To support Component you need only `component.json` (like `bower.json`) in project repo (no special publish commands).

A lot of npm libraries contains `component.js`: underscore, mocha, async, jade.

I make this pull request, because Autoprefixer 1.0 will use `source-map` and `component.json` in `source-map` is required to build `autoprefixer-rails` standalone file.