Merge branch 'drop-username-tree-row' into 'master'

Drop the user name from tree row to improve readability of commit messages

Follow up to MR !579

/cc @dzaporozhets

See merge request !1124

app/views/projects/tree/_tree_commit_column.html.haml

 %span.str-truncated
-  %span.tree_author= commit_author_link(commit, avatar: true, size: 16)
   = link_to_gfm commit.title, namespace_project_commit_path(@project.namespace, @project, commit.id), class: "tree-commit-link"