Add test for Google font css

Proofer says:
> https://fonts.googleapis.com/css?family=Open+Sans:300,300italic,400,400italic,600,600italic|Noto+Serif:400,400italic,700,700italic|Droid+Sans+Mono:400 is an invalid URL

My browser and wget can access the resource (200). Is this an encoding issue?

This solves the issue.