Thanks a lot to Bartosz Kiełczewski for his springboot tutorial (see : http://kielczewski.eu/2014/04/developing-restful-web-service-with-spring-boot/)
I added these topics :

1) I replaced maven configuration by gradle.
2) I created an ExampleController to test a POC with 2 differents services. This controller return an "Hello World"
3) I completed the UserController to achieve a restful-web-service with the POST-PUT-GET-DELETE method.
4) I added an IHM to display a paginated list of the created users. I used Spring MVC/thymeleaf/bootstrap to do that

You can start the application with the "gradle bootRun" command line
I advice to test the application with the postman chrome plugin

Requirement :
Java 8
Gradle : 2.5

Quick start :
gradle bootRun