Have log_out method return json.

This commit helps improve the discourse_api experience so that we can
check the json response if it was a success or not. This commit also
checks that a 404 is sent instead of a 500 if a bad user_id is passed
in.

app/controllers/admin/users_controller.rb

@@ -66,10 +66,14 @@ class Admin::UsersController < Admin::AdminController
   end
 
   def log_out
+    if @user
       @user.auth_token = nil
       @user.save!
       MessageBus.publish "/logout", @user.id, user_ids: [@user.id]
-    render nothing: true
+      render json: success_json
+    else
+      render json: {error: I18n.t('admin_js.admin.users.id_not_found')}, status: 404
+    end
   end
 
   def refresh_browsers

config/locales/client.en.yml

@@ -1887,6 +1887,7 @@ en:
         create: 'Add Admin User'
         last_emailed: "Last Emailed"
         not_found: "Sorry, that username doesn't exist in our system."
+        id_not_found: "Sorry, that user id doesn't exist in our system."
         active: "Active"
         show_emails: "Show Emails"
         nav:

spec/controllers/admin/users_controller_spec.rb

@@ -360,6 +360,29 @@ describe Admin::UsersController do
       end
     end
 
+    context 'log_out' do
+      before do
+        @reg_user = Fabricate(:user)
+      end
+
+      it 'returns JSON' do
+        xhr :put, :log_out, user_id: @reg_user.id
+        ::JSON.parse(response.body).should be_present
+      end
+
+      it "returns success" do
+        xhr :put, :log_out, user_id: @reg_user.id
+        response.should be_success
+        json = ::JSON.parse(response.body)
+        json['success'].should == "OK"
+      end
+
+      it "returns 404 when user_id does not exist" do
+        xhr :put, :log_out, user_id: 123123
+        response.should_not be_success
+      end
+    end
+
     context 'block' do
       before do
         @reg_user = Fabricate(:user)