Display renamed files in diff views

Created by: mr-vinn

Show both the old and new filenames when viewing the diff for a renamed file, as suggested on feedback.gitlab.com.

This depends on a change to gitlab_git; file rename detection is enabled there in merge request 6 on gitlab.com. However, this change shouldn't break the existing diff view in the meantime.

Here are screen prints of some commits from the gitlab-shell repo. The "before" view is the same with either of these combinations of gitlab and gitlab_git:

• gitlabhq/master gitlab and gitlabhq/master gitlab_git
• mr-vinn/diff-renames gitlab and gitlabhq/master gitlab_git

The "after" view requires mr-vinn/diff-renames gitlab and mr-vinn/rugged-diff-options gitlab_git

Before

After