We now follow a more consistent naming scheme for the methods in repository that are driven by the following guidelines:
* Methods referring to an identifier now all end on …ById(…).
* Methods taking or returning a collection are named …All(…)
That results in the following renames:
* findOne(…) -> findById(…)
* save(Iterable) -> saveAll(Iterable)
* findAll(Iterable<ID>) -> findAllById(…)
* delete(ID) -> deleteById(ID)
* delete(Iterable<T>) -> deleteAll(Iterable<T>)
* exists() -> existsById(…)
As a side-effect of that, we can now drop the Serializable requirement for identifiers.
Updated CRUD method detection to use the new naming scheme and moved the code to Java 8 streams and Optional. Adapted RepositoryInvoker API to reflect method name changes as well.