DATAJPA-419 - Adapt to new non-lazy-instantiation model of repositories.

Mostly mayor cleanups the way test cases bootstrap the repositories as they're now instantiated eagerly.
DATAJPA-424 - Fixed alias detection in manually defined queries using SpEL.

ExpressionBasedStringQuery now resolves and evaluates SpEL expressions of the actual query in the constructor and passes the resolved query to the StringQuery constructor. This enables the alias detection mechanism to work properly.

Original pull request: #51
DATAJPA-265 - Support for auditing configuration via JavaConfig.

Introduces the necessary infrastructure to configure auditing with JPA via JavaConfig using @EnableJpaAuditing.

Original pull request: #50.
DATAJPA-265 - Improve implementation of AuditingBeanFactoryPostProcessor.

Polished the implementation of AuditingBeanFactoryPostProcessor to selectively add depends-on clauses to all bean definitions that will result in EntityManagerFactory instances eventually. Added unit tests to verify intended behavior for Java based configuration. Polished newly integrated test cases.

Removed obsolete code from AuditingEntityListener. Added configuration sample snippet. Polished reference documentation.

Original pull request: #50.
DATAJPA-265 - Further polishing.

Original pull request: #50.
DATAJPA-426 - Improve extensibility of SimpleJpaRepository.

Made a few originally private method protected to allow usage from sub-classes.