Fixed Rubocop offenses

app/controllers/dashboard/snippets_controller.rb

app/controllers/projects/notes_controller.rb

app/controllers/projects/protected_branches_controller.rb

app/helpers/application_helper.rb

app/helpers/external_wiki_helper.rb

app/helpers/gitlab_markdown_helper.rb

app/helpers/projects_helper.rb

app/helpers/tree_helper.rb

app/mailers/notify.rb

app/models/application_setting.rb

app/models/concerns/token_authenticatable.rb

app/models/merge_request.rb

app/models/namespace.rb

app/models/project.rb

app/models/project_services/bamboo_service.rb

app/models/project_services/flowdock_service.rb

app/models/project_services/gemnasium_service.rb

app/models/project_services/teamcity_service.rb

app/models/user.rb

app/services/merge_requests/refresh_service.rb