Possible Gutenberg Plugin Incompatibility and Feature Request

Hi there. Thanks for the great plugin.

Using the latest version of Gutenberg seems to conflict with this plugin. The code block was a little messed up, and when I disabled Gutenberg to fix it, the code blocks were invalidated and I had to do some simple conversion to get them back working.

Also I have a feature request. Can you please add a rel attribute for the language so we can style the language output like: https://gist.github.com/ronalfy/2dbb84ceee04328d6bca98b21df7fb1c

Thanks a lot.

Ronald Huereca