App should be as simple as possible for beginners

This fix the following error :

   "setAttribute: Non-serializable attribute owner"

In the following context :

  - hsql database configuration (updating data-access.properties only)

  - mvn clean install bees:run (cloudbees local run)

see: https://jira.springsource.org/browse/DATAJPA-292

Use ContentNegotiationManagerFactoryBean
Use URI variables in redirect URLs

In that way we don't need a dedicated config file for the Service layer