Merge branch 'afontaine/deployment-approval' into 'master'

...assets/javascripts/environments/components/deployment.vue

...ascripts/environments/components/new_environment_item.vue

...ascripts/environments/components/new_environments_app.vue

app/assets/javascripts/environments/index.js

app/assets/javascripts/environments/new_index.js

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

doc/ci/environments/deployment_approvals.md

ee/app/assets/javascripts/api.js

...ascripts/environments/components/environment_approval.vue

ee/app/serializers/ee/deployment_entity.rb

ee/spec/frontend/api_spec.js

ee/spec/frontend/environments/environment_approval_spec.js

ee/spec/frontend/environments/mock_data.js

ee/spec/frontend/environments/new_environment_item_spec.js

ee/spec/serializers/ee/deployment_entity_spec.rb

locale/gitlab.pot

spec/frontend/environments/new_environment_item_spec.js

spec/frontend/environments/new_environments_app_spec.js