Add support for @javax.transaction.Transactional

_From [cup@gamblify.com](https://code.google.com/u/107492071264981384410/) on March 04, 2014 10:13:53_

Description of the issue: Guice-Persist currently only supports `@`com.google.inject.persist.Transactional. It would be nice if it could support `@`javax.transaction.Transactional as well for transactions. Steps to reproduce: 1. Create a service class with a method annotated with `@`javax.transaction.Transactional
2. Use method and see that the transaction does not work.

_Original issue: http://code.google.com/p/google-guice/issues/detail?id=797_