adding comments

 * The double in DoubleEntityManager has a 'double' meaning:
 * 
 * 1) There are 2 entitymanagers which are connecting to the VME Oracle
DB. The
 * first is through vme-web and the next through rsg-web.
 * 
 * 2) When the RSG entitymanager changes the VME DB, the vme-web
EntityManager
 * needs to be replaced with another one. Apparentely replacing is the
simplest
 * and less risky way. Other methods have been explored like refresh,
clear but
 * it all led to all sorts of Hibernate consistency complains.
 * 
 * This class gives the possibility to create a new one, when the RSG
has
 * updated the underlying DB.
 * 
 * Apparently JPA does not envisage the use of 2 entitymanager to the
same DB.
 * DoubleEntityManager solves the related issues when you do use 2
 * entitymanagers.
 *