PROTON-302: added negative testing for messenger ssl; added proper validation of messenger credentials; fixed the java work queue and transport work queue implementation; added the missing Delivery.clear() method to proton-j

git-svn-id: https://svn.apache.org/repos/asf/qpid/proton/trunk@1539013 13f79535-47bb-0310-9956-ffa450edef68