Javascript-SDK - 2.0.3

* Remove [`request`](https://www.npmjs.com/package/request) dependency ([#98](https://github.com/optimizely/javascript-sdk/pull/98))
* Add package-lock.json ([#100](https://github.com/optimizely/javascript-sdk/pull/100))
* Input validation in Activate, Track, and GetVariation methods ([#91](https://github.com/optimizely/javascript-sdk/pull/91) by [@mfahadahmed](https://github.com/mfahadahmed))

https://github.com/optimizely/javascript-sdk/releases/tag/v2.0.3