Refactor sorting in project

app/controllers/admin/groups_controller.rb

app/controllers/admin/users_controller.rb

app/controllers/application_controller.rb

app/controllers/dashboard_controller.rb

app/helpers/sorting_helper.rb

app/models/concerns/issuable.rb

app/models/concerns/sortable.rb

app/models/group.rb

app/models/project.rb

app/models/user.rb

app/views/admin/groups/index.html.haml

app/views/admin/projects/index.html.haml

app/views/admin/users/index.html.haml

app/views/dashboard/_projects_filter.html.haml

app/views/explore/groups/index.html.haml

app/views/explore/projects/index.html.haml

app/views/shared/_sort_dropdown.html.haml

features/steps/groups.rb