Support of JACC 3.1.1.2 - Linking of Policy Contexts

Geronimo needs to support 3.1.1.2 of the JACC spec which states:

"In the J2EE security model, principal-to-role mappings have application scope;
that is, the same principal-to-role mappings must apply in the access decisions
applied at all of the modules (that may represent separate policy contexts) that
comprise an application. Same application policy contexts must be associated by
calling the PolicyConfiguration.linkConfiguration method."