Social icons should include icons for services

[phidias51]

The social icons should include icons for Google+, Facebook, Twitter and LinkedIn.

[rdrey]

I'm missing a basic share button. Luckily the core-iconset-svg is so easy to use, I rolled my own for now. But yes, please include some services, it should be possible to get the permission to use proprietary icons.

[hubgit]

It's strange that there are icons for services on the demo page, but not in social-icons.html.