Created helper to find out the weekend dates
new file:   app/helpers/time_helper.rb
modified:   app/models/activity.rb
Modified helper to calculate if date or a range is during a weekend
modified:   app/helpers/time_helper.rb
modified:   app/models/activity.rb
new file:   app/views/activities/_activity_link.html.erb
modified:   app/views/activities/index.html.erb