Functionality to display HOT progress

app/assets/stylesheets/style.css
- Add 'span.hot'.
app/helpers/application_helper.rb
- Add process_hotter().
'progresses#_form' to display help message for text input

app/views/progresses/_form.html.erb
- Modify to display parital 'shared/help_for_text_input'.
app/views/projects/_form.html.erb
- Move out the help message for text input to partial
  'shared/help_for_text_input'.
app/views/shared/_help_for_text_input.html.erb
- Newly created, taking over the above.