[eclipselink-dev] check in for fix for bug 221226

["Peter Krogh" <peter.krogh@xxxxxxxxxx>]

These three related bugs are fixed by this transaction.

221226 Support a provided classloader in EclipseLink JPA EntityManagerFactory Creation
	214769 DatasourceLogin.setPlatformClassName should take optional ClassLoader
	221225 EntityManagerSetupImpl should set PersistenceUnitInfo classloader on DatasourceLogin

Patch is on this bug - https://bugs.eclipse.org/bugs/show_bug.cgi?id=221226

This fix was written by Shaun Smith and Peter Krogh, and reviewed by Tom Ware.

New API:
	221226 adds a property called eclipselink.classloader.  
	/*
	 * Specify the classloader to use to create an EntityManagerFactory in the
       * property map passed to Persistence.createEntityManagerFactory.
       * This is a dynamic property, that can only be set at runtime in the property
       * map, and is not for use in the persistence.xml
       */