Provide ES6 modules in transpilation context
Provide ES6 modules in transpilation context

This change, ripped straight from [plugin-text](https://github.com/systemjs/plugin-text/blob/master/text.js), enables generation of ES6 modules in the case where transpilation is happening. This makes it possible to use plugins like the excellent [systemjs-hot-reloader](https://github.com/capaj/systemjs-hot-reloader) for a much smoother development experience.
KevCJones/plugin-scss,KevCJones/plugin-scss