revising tinymce font import syntax
* matches syntax used when importing Open Sans in LMS/Studio
* simplifies and moves syntax to modern Google Web Font standards
* maintains the http/https agnostic work
Merge pull request #2019 from edx/talbs/tinymce-fonts

TinyMCE: Updating Google Font Syntax
Add @tusbar to AUTHORS file

To acknowledge his help with refactoring URLs in our CSS to be
protocol-relative
Merge pull request #1975 from edx/db/revert-revert-https-fonts

Studio HTTPS Fonts (re-enable)