'projects#show' to display button to make Progress on today

app/controllers/progresses_controller.rb
- Alter load_project() to load @progress as well and rename
  it to load_project_and_progress().
- Add make_today().
app/models/progress.rb
- Add on_today?() and make_today().
app/views/progresses/_progress.html.erb
- Display button to make_today for Progress's not on today.
app/views/projects/_progress_list.html.erb
- Alter <th>'s colspan for links.
config/locales/ja.yml
- Add "make_today" under "helpers.link.progress", etc.