Add an official Spring / Guice example

[lukaseder]

There had been quite a bit of confusion recently around this rather misleading blog post here:
http://blog.uws.ie/2013/04/using-jooq-with-spring-transactions/

This post has a couple of flaws:

1. It is based on jOOQ 2.x
2. It is no longer maintained
3. It makes a couple of wrong assumptions about ExecuteListener
4. It doesn't correctly handle nested transactions
5. It doesn't correctly provide Connections to jOOQ

Users find this post through Google and then spread further confusion on the user group as can be seen here, in this rather long thread:
https://groups.google.com/forum/#!topic/jooq-user/L9lqjxXxv5s

We should get back in control of this part of the documentation and add our own (integration-tested) example to GitHub and to the manual