CE upstream: thursday

• both modified: app/assets/javascripts/vue_merge_request_widget/components/states/mr_widget_conflicts.js
• both modified: app/assets/stylesheets/framework/selects.scss
• both modified: app/models/concerns/repository_mirroring.rb
• both modified: app/serializers/merge_request_entity.rb
• both modified: app/services/emails/create_service.rb
• both modified: app/services/emails/destroy_service.rb
• both modified: config/initializers/1_settings.rb
• both modified: config/webpack.config.js
• both added: db/migrate/20141126120926_add_merge_request_rebase_enabled_to_projects.rb
• both added: db/migrate/20150827121444_add_fast_forward_option_to_project.rb
• both modified: db/schema.rb
• both modified: doc/ci/variables/README.md
• both added: doc/user/project/merge_requests/fast_forward_merge.md
• both modified: doc/user/project/merge_requests/index.md
• both modified: doc/workflow/README.md
• both added: features/project/ff_merge_requests.feature
• both added: features/steps/project/ff_merge_requests.rb
• both modified: locale/gitlab.pot
• both modified: spec/features/protected_branches_spec.rb
• both modified: spec/fixtures/api/schemas/entities/merge_request.json
• both modified: spec/lib/gitlab/path_regex_spec.rb
• both modified: spec/lib/gitlab/shell_spec.rb
• both modified: spec/serializers/merge_request_entity_spec.rb
• both modified: spec/support/update_invalid_issuable.rb
• both modified: spec/tasks/gitlab/backup_rake_spec.rb