ADD support for Cordova google-analytics-plugin

Currently only the GAPlugin for Cordova/Phonegap (https://github.com/phonegap-build/GAPlugin) is supported (#60 thanks to @mlegenhausen).

This plugin provides an integration of the google-analytics-plugin for Cordova/Phonegap: https://github.com/danwilson/google-analytics-plugin

Usage example:

Before you can start using you need to install the google-analytics-plugin for your platform. The instructions can be found on the homepage.

Then add the plugin file to your index.html file:

    <script src="angulartics-ga-cordova-google-analytics-plugin.js"></script>

Now add the module to your app configuration.

    angular.module('app', ['angulartics', 'angulartics.google.analytics.cordova']);

Then configure the plugin via:

    .config('googleAnalyticsCordovaProvider', function (googleAnalyticsCordovaProvider) {
      googleAnalyticsCordovaProvider.trackingId = 'XXX';
      googleAnalyticsCordovaProvider.debug = true; // default: false
    })

That's it you now have mobile google analytics running in your app.

Feedback is welcome!