Reorder package.json and add "files" field

[dada1134]

Now npm will ignore all files except those stated in the docs and index.js. This makes downloading this package a little faster for everyone.

[feross]

I personally don't think it's a good idea to ignore the test/ folder. That's documentation for the module that will now be missing when you're offline and need to look inside node_modules/ for the docs.

Ignoring huge test files is a good idea, but ignoring a few text files won't make a meaningful difference. npm install is primarily slow because of latency and roundtrips, in my experience.

Previous discussions:

nodejs/readable-stream#100
rvagg/through2#36
browserify/browserify#1093
browserify/sha.js#5
feross/string-to-stream#1
beatgammit/base64-js#16
mafintosh/csv-parser#43
feross/buffer#98
feross/is-buffer#12