Add associated project info to runner details output

doc/api/runners.md

@@ -116,6 +116,13 @@ Example response:
     "last_contact": "2016-01-25T16:39:48.066Z",
     "name": null,
     "platform": null,
+    "projects": [
+        {
+            "id": 1,
+            "name": "GitLab.org / GitLab Community Edition",
+            "path": "gitlab-org/gitlab-ce"
+        }
+    ],
     "revision": null,
     "tag_list": [
         "ruby",

lib/api/entities.rb

@@ -369,6 +369,12 @@ module API
       expose :id, :variables
     end
 
+    class RunnerProjectDetails < Grape::Entity
+      expose :id
+      expose :name_with_namespace, as: :name
+      expose :path_with_namespace, as: :path
+    end
+
     class Runner < Grape::Entity
       expose :id
       expose :description
@@ -381,6 +387,7 @@ module API
       expose :tag_list
       expose :version, :revision, :platform, :architecture
       expose :contacted_at, as: :last_contact
+      expose :projects, with: Entities::RunnerProjectDetails
     end
 
     class Build < Grape::Entity