NO-JIRA: Fix URL test to skip 'amqps' tests if 'amqps' is not recognized as a service name.

On some older Ubuntu with Java 6, 'amqps' is not recognized as a service name so
skip those tests in that case.

git-svn-id: https://svn.apache.org/repos/asf/qpid/proton/trunk@1627577 13f79535-47bb-0310-9956-ffa450edef68