If an application defines a custom RepositoryRestMvcConfiguration, all
Spring Boot defaults are lots. While this sounds sensible, it can be
confusing as Spring Boot exposes properties (`spring.data.rest.*`) that
are no longer honored.

RepositoryRestMvcBootConfiguration is now public and can be used as an
extension point for those who need to customize the Spring Data REST
configuration and keep boot's specific defaults.

Fixes gh-2392