Allow configuration of RowMapper by Type [DATAJDBC-166]

**[Jens Schauder](https://jira.spring.io/secure/ViewProfile.jspa?name=schauder)** opened **[DATAJDBC-166](https://jira.spring.io/browse/DATAJDBC-166?redirect=false)** and commented

It should be easily possible to configure a mapping from type to `RowMapper` used for methods with that return type


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**Referenced from:** pull request https://github.com/spring-projects/spring-data-jdbc/pull/33
