[core] google analytics api + generator

Google Analytics api for Dandelion cover
 - all basic fields (no plugin fields)
 - creating tracker
 - set general field
 - sending data (pageview, event, social, ...)
 - multi-tracker definition

 This generate an asset based on the configuration put throw the Google Analytics api

 GoogleAnalytics.on(request)
                 .defaultTracker("UA-XXXX-Y")
                 .set(GeneralField.anonymizeIp, "true")
                 .send().pageview();

 become

 (function(i,s,o,g,r,a,m){i['GoogleAnalyticsObject']=r;i[r]=i[r]||function(){(i[r].q=i[r].q||[]).push(arguments)},i[r].l=1*new Date();a=s.createElement(o),m=s.getElementsByTagName(o)[0];a.async=1;a.src=g;m.parentNode.insertBefore(a,m)})(window,document,'script','//www.google-analytics.com/analytics.js','ga');
 ga('create', 'UA-XXXX-Y', 'auto');
 ga('set', 'anonymizeIp', true);
 ga('send', 'pageview', {});