Refactor session creation and endpoint event firing

git-svn-id: https://svn.apache.org/repos/asf/tomcat/trunk@1437947 13f79535-47bb-0310-9956-ffa450edef68
Fix some exception handling TODOs

git-svn-id: https://svn.apache.org/repos/asf/tomcat/trunk@1437956 13f79535-47bb-0310-9956-ffa450edef68