You were scanning the wrong package in your EnableJpaRepositories. There is no org.mdacc.rists.cghub.ws.repository package. So, use this instead:
@EnableJpaRepositories("org.mda.rists.cghub.ws.repository")
Spring Boot does not require any specific code layout to work, however, there are some best practices that will help you. Check out the spring boot documentation on best practices of structuring your code.