PROTON-506: Added unit tests for C url parser

git-svn-id: https://svn.apache.org/repos/asf/qpid/proton/trunk@1576090 13f79535-47bb-0310-9956-ffa450edef68
PROTON-506: Fix C address URL parser to correctly identify the host component
if there is an '@' character in the path component.

git-svn-id: https://svn.apache.org/repos/asf/qpid/proton/trunk@1576091 13f79535-47bb-0310-9956-ffa450edef68