React 15.x support

added support for react 15.x and react-router 2.x

deps

deps:
lodash 4.6.1
babel 6.6

commonjs and babel 6

you are able to use this plugin with classic commonjs

var GoogleAnalytics = require('react-g-analytics');

react-router 2.x

Added support for react-router 2.x

0.1.17

ID parameter is optional
added set parameter (you can set other google analytics parameters like an anonymizeIp)
improved readme