Update Twitter and Facebook icons

[irock]

The Twitter icon uses a modified version of their old "lowercase t" logo which was taken out of use years ago.

For the sake of recognizably, I suggest using the bird icon straight from the official brand resources, and do the same for Facebook as well.

https://about.twitter.com/en_us/company/brand-resources.html
https://en.facebookbrand.com/facebookapp/assets/f-logo?audience=landing

• Issue Assigned from (none) to stefan

• Tags added: 4.1.0
• Status changed from New to Resolved

• 4.1.0