Suggestion: publish fewer files

I noticed that multiple versions of the library were being published to npm in this package: the unminified code, the minified code, and the legacy code.

I cleaned up the .npmignore a bit to remove some unnecessary files.

I also made a change to match my preference (and I think convention?) that the unminified version be published to npm.  I prefer to be able to trace into the libraries that I use (and get readable stack traces, when the case arises), and minify them all together manually before I deploy my npm-installed modules to the browser.

If you're dead-set on pushing minified code to npm, I can switch it back, but please consider just publishing the readable version to npm.

<3

- removed unnecessary node_modules line in .npmignore
- added ancillary test/build files to .npmignore
- changed package.json to publish the unminified version of the library