Add helper to_displaying_string() to delegate to newline2br()

app/helpers/application_helper.rb
- Add to_displaying_string() just to delegate arguments to
  newline2br() for now.
app/views/progresses/_progress.html.erb
app/views/progresses/index.html.erb
app/views/projects/index.html.erb
- Alter to call to_displaying_string() instead of newline2br().
app/views/projects/_project.html.erb
- Alter to call to_displaying_string() instead of newline2br().
- Move the links for the project above the project display to
  fix the location of the links to browse throught the projects.