Add Components module with reusable readers and writers

[radcortez]

• JdbcCursorItemReader
• JdbcBatchItemWriter

[radcortez]

@victoralc, here is a proposal to support reusable JDBC readers / writers.

There is still a lot missing here, namely, documentation, which I need to refactor, but I think you should be able to see how it works from the integration-test. Let me know if this works for you.

[victoralc]

Thanks, Roberto. I will take a look.