DATAJPA-438 - Removed custom ConversionService handling in JpaQueryExecution.

Spring Data Commons introduced a generic mechanism to post process the results of a repository method execution to potentially mitigate type differences between the result of the execution and the declared method return type. Thus we can remove the custom ConversionService usage implemented in JpaQueryExecution.

Related tickets: DATACMNS-483.
DATAJPA-517 - Defensive checks for CrudMethodMetadata in SimpleJpaRepository.

As CrudMethodMetadata is an optional dependency of SimpleJpaRepository we need to guard access to it with proper null checks.
DATAJPA-455 - Add support for stored procedure backed repository methods.

Added support for JPA 2.1 stored procedures mapping for repository methods. Introduced @Procedure annotation for declaring stored procedure metadata. Repository methods backed by stored procedures are represented as a StoredProcedureJpaQuery that is constructed by JpaQueryFactory#fromProcedureAnnotation.

Enhanced JpaQueryLookupStrategy to support @Procedure. Introduced StoredProcedureAttribute to capture the derived configuration for a stored procedure query.

The stored procedure needed for the tests is created via the schema-stored-procedures.sql script that is picked up by the customized DataSource definition in infrastructure.xml.

Added new test class UserRepositoryStoredProcedureTests to be able to exclude those tests for OpenJPA. OpenJPA tests don't work with hsqldb 2.x and use hsqldb 1.x instead which doesn't support stored procedures.

Original pull request: #80.
DATAJPA-499 - Querydsl now uses the null-handling configured on the Sort.Order.

We now propagate the null-handling hint defined in Order to an appropriate Querydsl null handling hint.

Original pull request: #82.
DATAJPA-522 - Forward port changelog entries from bugfix branch.
DATAJPA-522 - Update changelog.
DATAJPA-522 - Prepare 1.6.0.RC1.

Upgraded to Spring Data Parent 1.4.0.RC1 and Spring Data Commons 1.8.0.RC1. Switched to milestone repository.
DATAJPA-522 - Release version 1.5.0.RC1.
DATAJPA-522 - Prepare next development iteration.
DATAJPA-522 - After release cleanups.