Possibility to mark transaction as rollback only (patch)

_From [tomas.varaneckas](https://code.google.com/u/101190767943968272629/) on October 13, 2010 07:27:43_

This applies to "extensions/persist"

The following patch allows to mark transactions as rollback-only. It's useful in unit tests:

`@`Test
`@`Transactional(rollbackOnly = true)
public void testDatabaseStuff() throws Exception {
// do db manipulations
}

No data will be commited to db.

**Attachment:** [gist](https://gist.github.com/70fe3a43cfcff7090a8f)
   _[transaction.rollbackonly.diff](https://gist.githubusercontent.com/gissuebot/70fe3a43cfcff7090a8f/raw/f9ad1f7f96513c5496ba9947728c121b35e74567/transaction.rollbackonly.diff)_

_Original issue: http://code.google.com/p/google-guice/issues/detail?id=551_