Move files around for more logical organization.

(index -> bin/cli_tool).js, package.json
	-`index.js` was developed as a command-line tool, and thus:
		-belongs in `bin/`
		-should be specified in `package.json`'s `bin` property.

(lib/converter -> schema-mapper).js
	-Move the `converter` module to the package root and rename it
	after the package itself, as it'll serve as the main entry point
	for other Node modules.