Enable Angular Universal

[jussikinnula]

After Angular has been upgraded to Angular 4, maybe we should try to get server side rendering working.

This task has no priority, however, similar approach could be taken as is implemented on: https://github.com/jussikinnula/angular2-universal-wordpress

[jussikinnula]

New information about Angular Universal on Angular 4.0.0+:
https://github.com/angular/universal/tree/master/modules/ng-express-engine

[jussikinnula]

And most probably we should use Redis to store rendered page for some duration (use URL without any GET parameters as key). Angular Universal rendering is a bit slow. Other alternative would be use CDN, but for our purpose Redis would be just fine for now. There's example implementation on Twitter feed already.