[Tech Debt]: started the CLI work for PR#49

This pull requests includes the very basic work to start end-to-end testing the arithmetic CLI integration

https://github.com/jspm/jspm-cli/issues/49
Yeah a `lib/bundle.js` would be sensible.

`extract` and `transform` methods can stick around as exports then, with API documented in a comment. Perhaps `extractOperations` and `transformOperations` to be clearer or something like that.

Entry point is unnecessary, core can just export the bundle method:

```javascript
var bundle = require('./lib/bundle');
core.bundle = bundle.bundle;
```