Add support for Gitlab about codecopy

[Glennmen]

It seems that Gitlab is loading content (README, comments, ...) async and because of this CodeCopy is not able find any <pre> tags.
If anyone has any suggestions on how best to solve this, please tag me.

[katrinleinweber]

Does "async" mean that content is loaded even after the load event?

[Glennmen]

@katrinleinweber I haven't checked if it is after the load event, it is some form of lazy loading or AJAX calls to show the data. It is not in the initial DOM that CodeCopy currently looks at.
I only looked at it very briefly.

[katrinleinweber]

Hm :-/ GitLab itself is tracking a few issues that seem related to this one: https://gitlab.com/gitlab-org/gitlab-ce/issues/59812 & https://gitlab.com/gitlab-org/gitlab-ce/issues/43289

[Glennmen]

Would be cool if we can add support for it before they have it ;)