Add support for transactionManagerRef in EnableJdbcRepository [DATAJDBC-622]

**[Jens Schauder](https://jira.spring.io/secure/ViewProfile.jspa?name=schauder)** opened **[DATAJDBC-622](https://jira.spring.io/browse/DATAJDBC-622?redirect=false)** and commented


---

**Issue Links:**
- [DATAJDBC-321](https://jira.spring.io/browse/DATAJDBC-321) Multiple datasources support


**Referenced from:** pull request https://github.com/spring-projects/spring-data-jdbc/pull/245
