Add JNDI server support

[antoinesd]

JNDI server is mandatory if we want to add feature like #24 and JTA support.

[johnament]

I think there's some ways to do the integration without JNDI. Specifically, overriding the Bittronix integration in hibernate to not use JNDI to look up the user transaction. This would be true of other JTA impls out there. Narayana seems to be notorious for its use of JNDI so I'd be cautious to bring it in.

[antoinesd]

You're right, we could do without JNDI, but it may imply that we'll have to support specific integration should we have multiple JPA impl support later.
I have to check, but JPA support datasource addition in persistence.xml only thru JNDI lookup.

[johnament]

Also not true. We can implement PersistenceUnitInfo and provide the DataSource instance as needed.

[johnament]

Antoine and I spoke about this. We agreed, the best solution is to provide a "simple" JNDI like service for binding beans, probably just named beans, in a look up.