Add timestamp to API deployments responses

Adds the updated_at attribute to responses from the API deployments
endpoints.

changelogs/unreleased/add-timestamps-to-api-deployments-response.yml

+---
+title: Added timestamp (updated_at) to API deployments response
+merge_request: 17913
+author:
+type: added

doc/api/deployments.md

@@ -24,6 +24,7 @@ Example of response
 [
   {
     "created_at": "2016-08-11T07:36:40.222Z",
+    "updated_at": "2016-08-11T07:38:12.414Z",
     "deployable": {
       "commit": {
         "author_email": "admin@example.com",
@@ -83,6 +84,7 @@ Example of response
   },
   {
     "created_at": "2016-08-11T11:32:35.444Z",
+    "updated_at": "2016-08-11T11:34:01.123Z",
     "deployable": {
       "commit": {
         "author_email": "admin@example.com",
@@ -167,6 +169,7 @@ Example of response
   "ref": "master",
   "sha": "a91957a858320c0e17f3a0eca7cfacbff50ea29a",
   "created_at": "2016-08-11T11:32:35.444Z",
+  "updated_at": "2016-08-11T11:34:01.123Z",
   "user": {
     "name": "Administrator",
     "username": "root",

lib/api/entities.rb

@@ -1474,7 +1474,7 @@ module API
     end
 
     class Deployment < Grape::Entity
-      expose :id, :iid, :ref, :sha, :created_at
+      expose :id, :iid, :ref, :sha, :created_at, :updated_at
       expose :user,        using: Entities::UserBasic
       expose :environment, using: Entities::EnvironmentBasic
       expose :deployable,  using: Entities::Job

spec/fixtures/api/schemas/public_api/v4/deployment.json

@@ -6,6 +6,7 @@
     "ref",
     "sha",
     "created_at",
+    "updated_at",
     "user",
     "deployable"
   ],
@@ -15,6 +16,7 @@
     "ref": { "type": "string" },
     "sha": { "type": "string" },
     "created_at": { "type": "string" },
+    "updated_at": { "type": "string" },
     "user": {
       "oneOf": [
         { "type": "null" },