Use map-stream instead of event-stream / Fix .travis.yml

* I replaced [event-stream](https://github.com/dominictarr/event-stream) with [map-stream](https://github.com/dominictarr/map-stream). [`es.map()` is just an alias for map-stream](https://github.com/dominictarr/event-stream/blob/480c38d08f5dffa34c41ac737456a3ea98f58d04/index.js#L12).
* I updated [lodash](https://www.npmjs.org/package/lodash), [chai](https://www.npmjs.org/package/chai), [mocha](https://www.npmjs.org/package/mocha) and [gulp](https://www.npmjs.org/package/gulp).
* I removed version 0.9 and 0.12 from `.travis.yml`. [Travis CI doesn't support them](http://docs.travis-ci.com/user/languages/javascript-with-nodejs/#Provided-Node.js-Versions).