Include commit message in page title.

app/views/projects/commit/show.html.haml

-- page_title @commit.id, "Commits"
+- page_title "#{@commit.title} (#{@commit.short_id})", "Commits"
 = render "commit_box"
 = render "projects/diffs/diffs", diffs: @diffs, project: @project
 = render "projects/notes/notes_with_form"