Adds allowLinker and autoLink to google-analytics.initializeUniversal() ...

Adds `allowLinker` and `autoLink` to `google-analytics.initializeUniversal()` `options` parameter.

 * `allowLinker` is boolean and includes `{allowLinker: true}` if set to `true`.
 * `autoLink` should be an Array of domain names, and includes the linker module then enables autolinking for links/forms to the `autoLink` domains. 

See https://developers.google.com/analytics/devguides/collection/analyticsjs/cross-domain