FELIX-4318 - prepare for initial release of JAAS Bundle

Reformatting. No other change made

git-svn-id: https://svn.apache.org/repos/asf/felix/trunk@1564642 13f79535-47bb-0310-9956-ffa450edef68
FELIX-4414 - Empty string value in jaas.realm should also trigger default

Checking for empty string in service reference properties also. Also added a testcase for Util class

git-svn-id: https://svn.apache.org/repos/asf/felix/trunk@1564643 13f79535-47bb-0310-9956-ffa450edef68