FELIX-3935 - Testcases for JAAS integration

Done the basic setup required for using Pax Exam. The pattern used is similar to used in SCR module. As next step we just need to implement different scenarios supported by this module.

Also adding a constant class to collect constant required for using jAAS support

git-svn-id: https://svn.apache.org/repos/asf/felix/trunk@1453297 13f79535-47bb-0310-9956-ffa450edef68